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339 Cards in this Set
- Front
- Back
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Major gases and their % in the atmosphere
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Nitrogen (78.1), molecular oxygen (20.9), argon (0.9)
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Atmospheric layers
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Troposphere, stratosphere, mesosphere, thermosphere, exosphere
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Troposphere characteristics
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Altitude: 0-11 km, air temperature decreases as altitude increases, convective motions, weather, 80% of atmosphere
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Tropopause
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Altitude where the minimum temperature occurs; border between troposphere and stratosphere
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Tropopause altitude
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Ranges from 8-9 km (polar regions), 11 km (mid latitudes), 15-16 km (tropics)
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Why does temperature decrease with altitude in troposphere?
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Air at the ground surface absorbs heat from the earth's surface; warm air rises, volume expands, decreasing temperature
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Stratosphere characteristics
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Altitude: tropopause to 50 km, weak vertical mixing and long residence times, active chemistry (ozone), absorbtion of solar ultraviolet radiation
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Stratosphere and temperature
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temperature increase to about 50 km
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Stratopause
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Altitude of maximum temperature of stratosphere, about 50 km
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Mesosphere characteristics
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Temperature decreases with altitude to about 85 to 90 km, atmosphereic chemistry driven by UV light efficient
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Mesopause
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Temperature minimum, 85-90 km
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Thermosphere
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Temperature increase with altitude, low atmospheric density
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Regions of the elecromagnetic spectrum
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Gamma rays, x-rays, UV, visible, infrared, microwaves, radio waves
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Gamma Rays
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very short wavelength, <0.1 nm, very high energy per photon
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X-rays
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0.1-10 nm wavelength, high energy per photon
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Ultraviolet
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10-400 nm wavelength, high/medium energy per photon
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Visible
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400-780 nm, medium/low energy per photon
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Infrared
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780-20,000 nm wavelength, low energy per photon
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Microwaves, radio waves
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>20,000 nm wavelength, very low energy per photon
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Solar constant
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SE, the total solar energy crossing a unit area per unit time at the top of the earth's atmosphere
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Budget of solar radiation
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absorption at ground (49%), absorption in atmosphere (20%), reflection to space (31%)
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Stefan-Boltzman Radiation Law
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specifies the total radiant energy flux emitted by a surface, does not address how energy is distributed over wavelength
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Effective radiating temperature
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provides just enough cooling to space to balance the heating from absorption of sunlight
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Greenhouse effect
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atmosphereic polyatomic gases absorb longwave radiation emitted by ground; longwave energy re-emitted to space and downward to be absorbed by ground. This extra energy makes surface warmer than it would otherwise be.
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Seasonal cycle, mechanisms
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annual cycle in temperature in which variation is greater with increasing latitude. Caused by tilt of earth's axis and rotation around sun.
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Saturation vapor pressure
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water vapor abundanceat which a given volume of air holds the maximum amount of water vapor; water vapor past this point will condense. Temperature-dependent.
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Relative humidity
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actual water vapor pressure expressed as percentage of the maximum possible water vapor pressure at a given temperature
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Dew point temperature
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The temperature to which a given parcel of air must be cooled, at constant barometric pressure, for water vapor to condense into water.
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Dry adiabatic lapse rate
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a rising air parcel cools by 9.8 K per km increase in altitude provided water vapor is not condensing to liquid.
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Moist adiabatic lapse rate
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rising air parcel with water vapor condensing; condensation releases heat, but expansional cooling is still taking place. No universal value (it's <dry rate) because it depends on amount of water vapor condensing.
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Lifting condensation level
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Specific altitude at which relative humidity first equals 100% for a rising parcel of air (i.e., point at which moist adiabatic lapse rate begins); corresponds to bottom of developing clouds.
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What affects LCL
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initial conditions; low r = high LCL, high r = low LCL. Implications – clouds can form over wide range of altitudes
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Origins of rising air
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thermal convection, orographic lifting, frontal activity, low pressure systems
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thermal convection causes rising air
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sunlight heats earth's surface, some areas absorb more energy than others, air warms above these areas and rises
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orographic lifting causes rising air
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air near the surface is forced to flow over objects in its path; prevailing winds force air upward
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frontal activity causes rising air
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different air masses with different temperatures and water vapor contents intersect, parcels of warmer air are forced upward along the front
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Low-pressure weather systems cause rising air
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lower pressures cause air parcels to expand and rise
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mechanisms for forming raindrops
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Collision-coalescence, bergeron process
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Collision-coalescence process
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clouds above freezing, condensation creates small # of large droplets and many small droplets, updrafts support small droplets but large descend due to gravity, as large droplets descend they collide and form raindrops.
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Complication of the collision-coalescence process
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coalescence is difficult to describe; many droplets flow around each other or collide but do not coalesce
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Bergeron process
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clouds contain ice and supercooled liquid (below freezing); Psat over ice < Psat over liquid; therefore liquid droplets evaporate and vapor condenses on ice particles; ice particles grow and fall (often melt before hitting ground)
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four forces that prodcue wind systems
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pressure gradient force, coriolis force, centrifugal force, friction
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Pressure gradient force
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air moves from regions of high pressure to regions of low pressure; difference in pressure divided by distance
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Horizontal pressure gradient – why
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horizontal pressure gradient exists in mid to upper troposphere due to temperature variations from pole to equator
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Pressure gradient and Hadley circulation
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equator heated, air rises, move to poles under pressure gradient, cool, and sink; cool air flows back to equator to take place of air rising there.
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Hadley circulation – why is it unrealistic
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considers only vertical motions and flow from equator to poles, no w-e winds
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Coriolis force
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arises because wind speed and direction measured relative to rotating planet; bends path of moving objects to the right of direction of movement (northern hemisphere); magnitude depends on air velocity measured rel to ground; affects air moving from high pressure to low pressure; important for motions that exist on timescales of 24 hours or longer
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Centrifugal force
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when a mass moves in a curved path, it experiences force directed outward, away from center of rotation; magnitude related to speed and radius of path; influences horizontal air flow around weather systems
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Friction
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force that opposes motion; in atmosphere from interaction w earth's surface, molecular viscosity, eddy viscosity (turbulence)
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Forces acting together to produce winds
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pressure gradient force pushes air parcel towards center of pressure low, coriolis force deflects motion to the right depending on wind speed, centrifugal force points outward and opposes pressure gradient force, all forces in balance when air flows counterclockwise parallel to isobars
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Geostrophic wind
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balance between the pressure gradient and Coriolis forces applied to the global circulation; pressure gradient force pointing to the north is balanced by a Coriolis force pointing to the south in the Northern Hemisphere. Winds blowing under these conditons are “geostrophic”
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Three-cell general circulation model
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more complex model of atmospheric circulation; three cells redistribute energy – hadley, farrel, polar cells
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Horse latitudes – where and why
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Where Hadley cells close (30 latitudes), cool dry air sinks to suface; some air moves equatorward and some poleward, forming divergence at ground level and standing high pressure zone (subtropical high)
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Notheasterly trades
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caused by equatorward ground flow as cool dry air moves back to equator
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Ferrel cell
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causes surface westerlies, 30-60 latitudes
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Polar cell
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60-90 latitudes, strong coriolis force and presence of jet streams make polar cell unsteady
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subtropical highs
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sinking air from closed Hadley cell, associated with deserts (high pressure = no clouds)
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Jet streams
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swiftly flowing air currents thousands of km long, few hundred km wide, few km thick.
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Jet streams – avg wind speeds
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Often >100 knots, occasionally >200 knots
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Jet streams – where found
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tropopause, between 10-15 km altitude, although this may vary
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Two jet streams
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Subtropical and polar front
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Jet streams – flow direction
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generally a wavy, west-east pattern. Polar jet stream loops may even merge with subtropical jet stream, or even split in two
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Jet streams – global transfer of heat
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Jet streams are a major transporter of heat around the globe, as well as pollutants and volcanic ash
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Jet streams – how form
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Rapid horizontal change in temperature produces a rapid change in pressure. The sudden change in pressure along the front sets up a steep pressure gradient that intensifies the wind speed and causes the jet stream.
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Monsoon
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wind system that changes direction seasonally, blowing from one direction in summer and from the opposite direction in winter. Significant in eastern and southern Asia.
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Monsoon – why?
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differential heating of land vs air in summer vs winter.
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Monsoon – winter
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large, shallow high-pressure area develops over colder continental siberia, producing anticyclone with air flowing out over indian ocean. Dry weather
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Monsoon – summer
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shallow thermal low develops over the continental interio as land heats more than water, producing cyclone that moves from ocean to land, bringing moisture into the continent. wet, rainy days with winds blow from sea to land for southeastern Asia.
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Middle atmosphere – definition
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the region from tropopause (10-16 km) to the homopause (at approximately 110 km); eddy processes keep the constituents well mixed and ionization plays minor role
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Middle atmosphere – major trace gases
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water vapor, CO2, ozone
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Stratosphere – regions
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(1) the tropics, 20°N to 20°S; (2) the middle latitudes or "surf zone"; (3) the polar vortex; and (4) the lowermost stratosphere.
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Stratosphere – the tropics
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20°N to 20°S, ozone photochemical source region due to ultraviolet radiation, ozone transported out of this region and poleward by a broad circulation pattern.
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Startosphere – surf zone
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Middle latitudes, characterized by a turbulent mixture of air masses, each of which contain differing amounts of ozone due to weather systems in the middle latitudes mixing tropical (high ozone) and polar (low ozone) air.
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Stratosphere – polar vortex
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In winter, stratospheric winds typically blow from west to east (the westerlies), jet stream occurs in winter along the polar night terminator, called the polar night jet. The region poleward of the polar night jets are polar vortex, a region of air isolated from the rest of the stratosphere where the long polar night allows extremely cold temperatures to develop.
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Stratosphere – lowermost stratosphere
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A special region of the stratosphere that contains a mixture of both tropospheric and stratospheric air, delineated on the bottom by the tropopause and at the top by the 380 K potential temperature surface. In the tropics, the lowermost stratosphere is separated on the bottom at the core of the subtropical jet stream.
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Brewer-Dobson circulation – definition
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slow meridional atmospheric circulation from tropics into middle and polar latitudes.
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Major gases and their % in the atmosphere
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Nitrogen (78.1), molecular oxygen (20.9), argon (0.9)
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Brewer-Dobson circulation – description
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Rising in tropics from troposphere to stratosphere, poleward transport in stratosphere, descending motion in stratospheric middle and polar latitudes.
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Brewer-Dobson circulation – descending air fate
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Middle latitudes - descending air is transported back into the troposphere, polar latitude - descending air is transported into the polar lower stratosphere, where it accumulates.
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Atmospheric layers
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Troposphere, stratosphere, mesosphere, thermosphere, exosphere
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Brewer-Dobson circulation – dehydration
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Dehydration can occur by condensation and precipitation as a result of cooling to temperatures below -80°C. The lowest values of water are found just near the tropical tropopause.
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Troposphere characteristics
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Altitude: 0-11 km, air temperature decreases as altitude increases, convective motions, weather, 80% of atmosphere
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Brewer-Dobson circulation – transport of ozone and trace gases
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This type of circulation explains observed high ozone concentrations in the lower stratosphere polar regions, far from the photochemical source region in the tropical middle stratosphere; also explains north-south distributions of long lived constituents like nitrous oxide and methane.
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Tropopause
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Altitude where the minimum temperature occurs; border between troposphere and stratosphere
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QBO – definition
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Equatorial Quasi-Biennial Oscillation; a long-term oscillation that overwhelms the seasonal cycle of zonal mean winds in equatorial stratosphere (below 35 km); not directly linked to the march of the seasons, somewhat irregular period (averaging 27 months),
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Major gases and their % in the atmosphere
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Nitrogen (78.1), molecular oxygen (20.9), argon (0.9)
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QBO – mechanisms
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Equatorially trapped Kelvin waves provide the westerly momentum and Rossby-gravity waves provide easterly momentum and these effects combine to produce the QBO oscillation.
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Tropopause altitude
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Ranges from 8-9 km (polar regions), 11 km (mid latitudes), 15-16 km (tropics)
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Atmospheric layers
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Troposphere, stratosphere, mesosphere, thermosphere, exosphere
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Polar vortex
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A persistent, large-scale cyclone located near one or both of a planet's geographical poles. On Earth, the polar vortices are located in the middle and upper troposphere and the stratosphere. They surround the polar highs and are part of the polar front. More stable in Antarctic than in Arctic due to landmass distribution.
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Troposphere characteristics
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Altitude: 0-11 km, air temperature decreases as altitude increases, convective motions, weather, 80% of atmosphere
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Why does temperature decrease with altitude in troposphere?
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Air at the ground surface absorbs heat from the earth's surface; warm air rises, volume expands, decreasing temperature
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SSW
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Stratospheric sudden warming: an event where the polar vortex of westerly (eastwards) winds in the Northern winter hemisphere abruptly (i.e. over the course of a few days) slows down or even reverses direction, accompanied by a rise of stratospheric temperature by several tens of kelvins
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Stratosphere characteristics
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Altitude: tropopause to 50 km, weak vertical mixing and long residence times, active chemistry (ozone), absorbtion of solar ultraviolet radiation
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Tropopause
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Altitude where the minimum temperature occurs; border between troposphere and stratosphere
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Water's unusual properties – cohesion
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means molecules stick to one another, leads to surface tension. Water's surface tension is highest, affects precipitaiton and cell biology
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Stratosphere and temperature
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temperature increase to about 50 km
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Tropopause altitude
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Ranges from 8-9 km (polar regions), 11 km (mid latitudes), 15-16 km (tropics)
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Water's unusual properties – adhesion
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means water sticks to other stuff, leads to wetting
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Stratopause
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Altitude of maximum temperature of stratosphere, about 50 km
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Why does temperature decrease with altitude in troposphere?
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Air at the ground surface absorbs heat from the earth's surface; warm air rises, volume expands, decreasing temperature
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Water's unusual properties – state
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exists in all 3 states at earth's surface
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Mesosphere characteristics
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Temperature decreases with altitude to about 85 to 90 km, atmosphereic chemistry driven by UV light efficient
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Stratosphere characteristics
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Altitude: tropopause to 50 km, weak vertical mixing and long residence times, active chemistry (ozone), absorbtion of solar ultraviolet radiation
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Water's unusual properties – dissolving
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dissolves more substances in greater quantities than any other common liquid, crucial to chemical, biological and physical processes.
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Mesopause
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Temperature minimum, 85-90 km
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Stratosphere and temperature
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temperature increase to about 50 km
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Water's unusual properties – density
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affected by temperature, salinity, and pressure; controls oceanic vertical circulation, seasonal stratification
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Stratopause
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Altitude of maximum temperature of stratosphere, about 50 km
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Thermosphere
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Temperature increase with altitude, low atmospheric density
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Regions of the elecromagnetic spectrum
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Gamma rays, x-rays, UV, visible, infrared, microwaves, radio waves
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Mesosphere characteristics
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Temperature decreases with altitude to about 85 to 90 km, atmosphereic chemistry driven by UV light efficient
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Water's unusual properties – heat capacity
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highest of all common solids and liquids, keeps climate on earth moderate
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Gamma Rays
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very short wavelength, <0.1 nm, very high energy per photon
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Mesopause
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Temperature minimum, 85-90 km
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Water's unusual properties – latent heat of vaporization
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highest of all common substances, major factor in heat transport in and btw ocean and atmosphere
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Thermosphere
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Temperature increase with altitude, low atmospheric density
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X-rays
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0.1-10 nm wavelength, high energy per photon
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Waves – definition
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transfers a disturbance from one part of a material to another, propagated through the material without any substantial overall motion of the material itself, without any significant distortion of the wave form, and with constant speed.
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Ultraviolet
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10-400 nm wavelength, high/medium energy per photon
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Wave motion
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A means whereby energy is transported across or through a material without any significant overall transport of the material itself.
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Regions of the elecromagnetic spectrum
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Gamma rays, x-rays, UV, visible, infrared, microwaves, radio waves
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Gamma Rays
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very short wavelength, <0.1 nm, very high energy per photon
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Visible
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400-780 nm, medium/low energy per photon
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Wave dispersion
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Waves of different wavelengths become dispersed, because those with greater wavelengths and longer periods travel faster than smaller waves.
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Wave interactions
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If two wave trains of similar wavelength and amplitude travel over the same sea area, they interact. Where they are in phase, displacement is doubled, whereas where they are out of phase, displacement is zero.
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Infrared
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780-20,000 nm wavelength, low energy per photon
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X-rays
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0.1-10 nm wavelength, high energy per photon
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Wave group velocity
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Interacting waves produce wave trains, travelling as a series of wave groups, each separated from adjacent groups by an almost wave-free region. Wave group speed in deep water is half the wave (phase) speed. In shallowing water, wave speed approaches group speed, until they become equal.
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Microwaves, radio waves
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>20,000 nm wavelength, very low energy per photon
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Ultraviolet
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10-400 nm wavelength, high/medium energy per photon
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Solar constant
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SE, the total solar energy crossing a unit area per unit time at the top of the earth's atmosphere
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Wind waves
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Gravity waves formed by the transfer of wind energy into water; less than 3 meters high; wavelengths from 60 to 150 meters are most common in the open sea.
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Visible
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400-780 nm, medium/low energy per photon
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Budget of solar radiation
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absorption at ground (49%), absorption in atmosphere (20%), reflection to space (31%)
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Tsunami
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Long-wavelength, shallow-water progressive waves caused by the rapid displacement of ocean water
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Infrared
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780-20,000 nm wavelength, low energy per photon
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Stefan-Boltzman Radiation Law
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specifies the total radiant energy flux emitted by a surface, does not address how energy is distributed over wavelength
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Two theories of tides
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Equilibrium and dynamic
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Microwaves, radio waves
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>20,000 nm wavelength, very low energy per photon
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Effective radiating temperature
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provides just enough cooling to space to balance the heating from absorption of sunlight
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Equilibrium theory of tides
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basic theory of tides that examines the balance and effects of the forces that allow a planet to stay in a stable orbit. Assumes that the seafloor does not affect tides, and that ocean conforms instantly to forces that act on it.
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Solar constant
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SE, the total solar energy crossing a unit area per unit time at the top of the earth's atmosphere
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Dynamic theory of tides
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adds fluid motion dynamics to equilibrium theory; reconciles observations with predictions. Includes seabed contour, wave inertia, and water viscosity.
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Greenhouse effect
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atmosphereic polyatomic gases absorb longwave radiation emitted by ground; longwave energy re-emitted to space and downward to be absorbed by ground. This extra energy makes surface warmer than it would otherwise be.
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Budget of solar radiation
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absorption at ground (49%), absorption in atmosphere (20%), reflection to space (31%)
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Stefan-Boltzman Radiation Law
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specifies the total radiant energy flux emitted by a surface, does not address how energy is distributed over wavelength
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Seasonal cycle, mechanisms
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annual cycle in temperature in which variation is greater with increasing latitude. Caused by tilt of earth's axis and rotation around sun.
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Tidal frequencies
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diurnal, semidiurnal, mixed
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Saturation vapor pressure
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water vapor abundanceat which a given volume of air holds the maximum amount of water vapor; water vapor past this point will condense. Temperature-dependent.
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Effective radiating temperature
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provides just enough cooling to space to balance the heating from absorption of sunlight
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Tidal dissipation – how
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bottom friction especially in shallow seas, by the flow over seamounts and mid-ocean ridges, and by the generation of internal waves over seamounts and at the edges of continental shelves.
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Greenhouse effect
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atmosphereic polyatomic gases absorb longwave radiation emitted by ground; longwave energy re-emitted to space and downward to be absorbed by ground. This extra energy makes surface warmer than it would otherwise be.
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Relative humidity
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actual water vapor pressure expressed as percentage of the maximum possible water vapor pressure at a given temperature
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Tidal dissipation – implications
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Tidal forces dissipate in the ocean, and much smaller amounts in the atmosphere and solid Earth. The dissipation increases the length of day by about 2.07 milliseconds per century, it causes the semimajor axis of moon's orbit to increase by 3.86cm/yr, and it mixes water masses in the ocean.
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Surface currents – definition
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water flowing horizontally in the upper most 400 meters, driven mainly by wind friction, above the pycnocline. Transport heat.
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Dew point temperature
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The temperature to which a given parcel of air must be cooled, at constant barometric pressure, for water vapor to condense into water.
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Seasonal cycle, mechanisms
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annual cycle in temperature in which variation is greater with increasing latitude. Caused by tilt of earth's axis and rotation around sun.
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Dry adiabatic lapse rate
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a rising air parcel cools by 9.8 K per km increase in altitude provided water vapor is not condensing to liquid.
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Saturation vapor pressure
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water vapor abundanceat which a given volume of air holds the maximum amount of water vapor; water vapor past this point will condense. Temperature-dependent.
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Surface currents – pattern
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roughly reflects surface wind patterns
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Moist adiabatic lapse rate
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rising air parcel with water vapor condensing; condensation releases heat, but expansional cooling is still taking place. No universal value (it's <dry rate) because it depends on amount of water vapor condensing.
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Ekman motion
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theoretical description of the motion of water affected by wind: effect of wind decreases with depth, and coriolis force deflects motion of the water away from direction of wind. Resulting pattern is an Ekman spiral.
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Relative humidity
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actual water vapor pressure expressed as percentage of the maximum possible water vapor pressure at a given temperature
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Ekman transport
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Total volume of water transported at right angles to the wind direction per second calculated by multiplying depth mean current speed by the thickness of the wind-driven layer.
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Lifting condensation level
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Specific altitude at which relative humidity first equals 100% for a rising parcel of air (i.e., point at which moist adiabatic lapse rate begins); corresponds to bottom of developing clouds.
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Dew point temperature
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The temperature to which a given parcel of air must be cooled, at constant barometric pressure, for water vapor to condense into water.
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Dry adiabatic lapse rate
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a rising air parcel cools by 9.8 K per km increase in altitude provided water vapor is not condensing to liquid.
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Ekman pumping
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upward movement of water in response to wind stress
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What affects LCL
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initial conditions; low r = high LCL, high r = low LCL. Implications – clouds can form over wide range of altitudes
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Moist adiabatic lapse rate
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rising air parcel with water vapor condensing; condensation releases heat, but expansional cooling is still taking place. No universal value (it's <dry rate) because it depends on amount of water vapor condensing.
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Intertial currents
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Rotational flows that continue after forces setting water in motion cease to act, influenced by Coriolis force. Water will continue to move until the energy supplied has been dissipated, mainly by internal friction.
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Origins of rising air
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thermal convection, orographic lifting, frontal activity, low pressure systems
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Lifting condensation level
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Specific altitude at which relative humidity first equals 100% for a rising parcel of air (i.e., point at which moist adiabatic lapse rate begins); corresponds to bottom of developing clouds.
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Geostrophic currents
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he currents that result when the horizontal pressure gradient force is balanced by the Coriolis force
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thermal convection causes rising air
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sunlight heats earth's surface, some areas absorb more energy than others, air warms above these areas and rises
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Dynamic topography
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Variations in the dynamic height of an isobaric surface
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What affects LCL
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initial conditions; low r = high LCL, high r = low LCL. Implications – clouds can form over wide range of altitudes
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orographic lifting causes rising air
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air near the surface is forced to flow over objects in its path; prevailing winds force air upward
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Geoid
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The equipotential surface that corresponds to the sea-surface of a hypothetical motionless ocean.
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frontal activity causes rising air
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different air masses with different temperatures and water vapor contents intersect, parcels of warmer air are forced upward along the front
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Origins of rising air
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thermal convection, orographic lifting, frontal activity, low pressure systems
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Low-pressure weather systems cause rising air
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lower pressures cause air parcels to expand and rise
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thermal convection causes rising air
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sunlight heats earth's surface, some areas absorb more energy than others, air warms above these areas and rises
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orographic lifting causes rising air
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air near the surface is forced to flow over objects in its path; prevailing winds force air upward
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mechanisms for forming raindrops
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Collision-coalescence, bergeron process
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Collision-coalescence process
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clouds above freezing, condensation creates small # of large droplets and many small droplets, updrafts support small droplets but large descend due to gravity, as large droplets descend they collide and form raindrops.
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frontal activity causes rising air
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different air masses with different temperatures and water vapor contents intersect, parcels of warmer air are forced upward along the front
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Complication of the collision-coalescence process
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coalescence is difficult to describe; many droplets flow around each other or collide but do not coalesce
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Low-pressure weather systems cause rising air
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lower pressures cause air parcels to expand and rise
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Bergeron process
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clouds contain ice and supercooled liquid (below freezing); Psat over ice < Psat over liquid; therefore liquid droplets evaporate and vapor condenses on ice particles; ice particles grow and fall (often melt before hitting ground)
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mechanisms for forming raindrops
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Collision-coalescence, bergeron process
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four forces that prodcue wind systems
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pressure gradient force, coriolis force, centrifugal force, friction
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Collision-coalescence process
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clouds above freezing, condensation creates small # of large droplets and many small droplets, updrafts support small droplets but large descend due to gravity, as large droplets descend they collide and form raindrops.
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Pressure gradient force
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air moves from regions of high pressure to regions of low pressure; difference in pressure divided by distance
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Complication of the collision-coalescence process
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coalescence is difficult to describe; many droplets flow around each other or collide but do not coalesce
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Horizontal pressure gradient – why
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horizontal pressure gradient exists in mid to upper troposphere due to temperature variations from pole to equator
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Bergeron process
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clouds contain ice and supercooled liquid (below freezing); Psat over ice < Psat over liquid; therefore liquid droplets evaporate and vapor condenses on ice particles; ice particles grow and fall (often melt before hitting ground)
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Pressure gradient and Hadley circulation
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equator heated, air rises, move to poles under pressure gradient, cool, and sink; cool air flows back to equator to take place of air rising there.
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four forces that prodcue wind systems
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pressure gradient force, coriolis force, centrifugal force, friction
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Pressure gradient force
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air moves from regions of high pressure to regions of low pressure; difference in pressure divided by distance
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Hadley circulation – why is it unrealistic
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considers only vertical motions and flow from equator to poles, no w-e winds
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Coriolis force
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arises because wind speed and direction measured relative to rotating planet; bends path of moving objects to the right of direction of movement (northern hemisphere); magnitude depends on air velocity measured rel to ground; affects air moving from high pressure to low pressure; important for motions that exist on timescales of 24 hours or longer
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Horizontal pressure gradient – why
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horizontal pressure gradient exists in mid to upper troposphere due to temperature variations from pole to equator
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Centrifugal force
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when a mass moves in a curved path, it experiences force directed outward, away from center of rotation; magnitude related to speed and radius of path; influences horizontal air flow around weather systems
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Pressure gradient and Hadley circulation
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equator heated, air rises, move to poles under pressure gradient, cool, and sink; cool air flows back to equator to take place of air rising there.
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Friction
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force that opposes motion; in atmosphere from interaction w earth's surface, molecular viscosity, eddy viscosity (turbulence)
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Hadley circulation – why is it unrealistic
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considers only vertical motions and flow from equator to poles, no w-e winds
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Forces acting together to produce winds
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pressure gradient force pushes air parcel towards center of pressure low, coriolis force deflects motion to the right depending on wind speed, centrifugal force points outward and opposes pressure gradient force, all forces in balance when air flows counterclockwise parallel to isobars
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Coriolis force
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arises because wind speed and direction measured relative to rotating planet; bends path of moving objects to the right of direction of movement (northern hemisphere); magnitude depends on air velocity measured rel to ground; affects air moving from high pressure to low pressure; important for motions that exist on timescales of 24 hours or longer
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Geostrophic wind
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balance between the pressure gradient and Coriolis forces applied to the global circulation; pressure gradient force pointing to the north is balanced by a Coriolis force pointing to the south in the Northern Hemisphere. Winds blowing under these conditons are “geostrophic”
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Centrifugal force
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when a mass moves in a curved path, it experiences force directed outward, away from center of rotation; magnitude related to speed and radius of path; influences horizontal air flow around weather systems
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Three-cell general circulation model
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more complex model of atmospheric circulation; three cells redistribute energy – hadley, farrel, polar cells
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Friction
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force that opposes motion; in atmosphere from interaction w earth's surface, molecular viscosity, eddy viscosity (turbulence)
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Horse latitudes – where and why
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Where Hadley cells close (30 latitudes), cool dry air sinks to suface; some air moves equatorward and some poleward, forming divergence at ground level and standing high pressure zone (subtropical high)
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Forces acting together to produce winds
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pressure gradient force pushes air parcel towards center of pressure low, coriolis force deflects motion to the right depending on wind speed, centrifugal force points outward and opposes pressure gradient force, all forces in balance when air flows counterclockwise parallel to isobars
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Notheasterly trades
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caused by equatorward ground flow as cool dry air moves back to equator
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Geostrophic wind
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balance between the pressure gradient and Coriolis forces applied to the global circulation; pressure gradient force pointing to the north is balanced by a Coriolis force pointing to the south in the Northern Hemisphere. Winds blowing under these conditons are “geostrophic”
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Ferrel cell
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causes surface westerlies, 30-60 latitudes
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Three-cell general circulation model
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more complex model of atmospheric circulation; three cells redistribute energy – hadley, farrel, polar cells
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Polar cell
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60-90 latitudes, strong coriolis force and presence of jet streams make polar cell unsteady
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Horse latitudes – where and why
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Where Hadley cells close (30 latitudes), cool dry air sinks to suface; some air moves equatorward and some poleward, forming divergence at ground level and standing high pressure zone (subtropical high)
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subtropical highs
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sinking air from closed Hadley cell, associated with deserts (high pressure = no clouds)
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Notheasterly trades
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caused by equatorward ground flow as cool dry air moves back to equator
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Jet streams
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swiftly flowing air currents thousands of km long, few hundred km wide, few km thick.
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Ferrel cell
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causes surface westerlies, 30-60 latitudes
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Jet streams – avg wind speeds
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Often >100 knots, occasionally >200 knots
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Polar cell
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60-90 latitudes, strong coriolis force and presence of jet streams make polar cell unsteady
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Jet streams – where found
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tropopause, between 10-15 km altitude, although this may vary
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subtropical highs
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sinking air from closed Hadley cell, associated with deserts (high pressure = no clouds)
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Two jet streams
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Subtropical and polar front
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Jet streams
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swiftly flowing air currents thousands of km long, few hundred km wide, few km thick.
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Jet streams – flow direction
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generally a wavy, west-east pattern. Polar jet stream loops may even merge with subtropical jet stream, or even split in two
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Jet streams – avg wind speeds
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Often >100 knots, occasionally >200 knots
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Jet streams – global transfer of heat
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Jet streams are a major transporter of heat around the globe, as well as pollutants and volcanic ash
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Jet streams – where found
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tropopause, between 10-15 km altitude, although this may vary
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Jet streams – how form
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Rapid horizontal change in temperature produces a rapid change in pressure. The sudden change in pressure along the front sets up a steep pressure gradient that intensifies the wind speed and causes the jet stream.
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Two jet streams
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Subtropical and polar front
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Monsoon
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wind system that changes direction seasonally, blowing from one direction in summer and from the opposite direction in winter. Significant in eastern and southern Asia.
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Jet streams – flow direction
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generally a wavy, west-east pattern. Polar jet stream loops may even merge with subtropical jet stream, or even split in two
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Monsoon – why?
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differential heating of land vs air in summer vs winter.
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Jet streams – global transfer of heat
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Jet streams are a major transporter of heat around the globe, as well as pollutants and volcanic ash
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Monsoon – winter
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large, shallow high-pressure area develops over colder continental siberia, producing anticyclone with air flowing out over indian ocean. Dry weather
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Jet streams – how form
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Rapid horizontal change in temperature produces a rapid change in pressure. The sudden change in pressure along the front sets up a steep pressure gradient that intensifies the wind speed and causes the jet stream.
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Monsoon – summer
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shallow thermal low develops over the continental interio as land heats more than water, producing cyclone that moves from ocean to land, bringing moisture into the continent. wet, rainy days with winds blow from sea to land for southeastern Asia.
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Monsoon
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wind system that changes direction seasonally, blowing from one direction in summer and from the opposite direction in winter. Significant in eastern and southern Asia.
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Middle atmosphere – definition
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the region from tropopause (10-16 km) to the homopause (at approximately 110 km); eddy processes keep the constituents well mixed and ionization plays minor role
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Monsoon – why?
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differential heating of land vs air in summer vs winter.
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Middle atmosphere – major trace gases
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water vapor, CO2, ozone
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Monsoon – winter
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large, shallow high-pressure area develops over colder continental siberia, producing anticyclone with air flowing out over indian ocean. Dry weather
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Stratosphere – regions
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(1) the tropics, 20°N to 20°S; (2) the middle latitudes or "surf zone"; (3) the polar vortex; and (4) the lowermost stratosphere.
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Monsoon – summer
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shallow thermal low develops over the continental interio as land heats more than water, producing cyclone that moves from ocean to land, bringing moisture into the continent. wet, rainy days with winds blow from sea to land for southeastern Asia.
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Stratosphere – the tropics
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20°N to 20°S, ozone photochemical source region due to ultraviolet radiation, ozone transported out of this region and poleward by a broad circulation pattern.
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Middle atmosphere – definition
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the region from tropopause (10-16 km) to the homopause (at approximately 110 km); eddy processes keep the constituents well mixed and ionization plays minor role
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Startosphere – surf zone
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Middle latitudes, characterized by a turbulent mixture of air masses, each of which contain differing amounts of ozone due to weather systems in the middle latitudes mixing tropical (high ozone) and polar (low ozone) air.
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Middle atmosphere – major trace gases
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water vapor, CO2, ozone
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Stratosphere – polar vortex
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In winter, stratospheric winds typically blow from west to east (the westerlies), jet stream occurs in winter along the polar night terminator, called the polar night jet. The region poleward of the polar night jets are polar vortex, a region of air isolated from the rest of the stratosphere where the long polar night allows extremely cold temperatures to develop.
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Stratosphere – regions
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(1) the tropics, 20°N to 20°S; (2) the middle latitudes or "surf zone"; (3) the polar vortex; and (4) the lowermost stratosphere.
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Stratosphere – lowermost stratosphere
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A special region of the stratosphere that contains a mixture of both tropospheric and stratospheric air, delineated on the bottom by the tropopause and at the top by the 380 K potential temperature surface. In the tropics, the lowermost stratosphere is separated on the bottom at the core of the subtropical jet stream.
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Stratosphere – the tropics
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20°N to 20°S, ozone photochemical source region due to ultraviolet radiation, ozone transported out of this region and poleward by a broad circulation pattern.
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Brewer-Dobson circulation – definition
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slow meridional atmospheric circulation from tropics into middle and polar latitudes.
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Startosphere – surf zone
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Middle latitudes, characterized by a turbulent mixture of air masses, each of which contain differing amounts of ozone due to weather systems in the middle latitudes mixing tropical (high ozone) and polar (low ozone) air.
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Brewer-Dobson circulation – description
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Rising in tropics from troposphere to stratosphere, poleward transport in stratosphere, descending motion in stratospheric middle and polar latitudes.
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Stratosphere – polar vortex
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In winter, stratospheric winds typically blow from west to east (the westerlies), jet stream occurs in winter along the polar night terminator, called the polar night jet. The region poleward of the polar night jets are polar vortex, a region of air isolated from the rest of the stratosphere where the long polar night allows extremely cold temperatures to develop.
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Brewer-Dobson circulation – descending air fate
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Middle latitudes - descending air is transported back into the troposphere, polar latitude - descending air is transported into the polar lower stratosphere, where it accumulates.
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Stratosphere – lowermost stratosphere
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A special region of the stratosphere that contains a mixture of both tropospheric and stratospheric air, delineated on the bottom by the tropopause and at the top by the 380 K potential temperature surface. In the tropics, the lowermost stratosphere is separated on the bottom at the core of the subtropical jet stream.
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Brewer-Dobson circulation – dehydration
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Dehydration can occur by condensation and precipitation as a result of cooling to temperatures below -80°C. The lowest values of water are found just near the tropical tropopause.
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Brewer-Dobson circulation – definition
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slow meridional atmospheric circulation from tropics into middle and polar latitudes.
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Brewer-Dobson circulation – transport of ozone and trace gases
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This type of circulation explains observed high ozone concentrations in the lower stratosphere polar regions, far from the photochemical source region in the tropical middle stratosphere; also explains north-south distributions of long lived constituents like nitrous oxide and methane.
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Brewer-Dobson circulation – description
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Rising in tropics from troposphere to stratosphere, poleward transport in stratosphere, descending motion in stratospheric middle and polar latitudes.
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QBO – definition
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Equatorial Quasi-Biennial Oscillation; a long-term oscillation that overwhelms the seasonal cycle of zonal mean winds in equatorial stratosphere (below 35 km); not directly linked to the march of the seasons, somewhat irregular period (averaging 27 months),
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Brewer-Dobson circulation – descending air fate
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Middle latitudes - descending air is transported back into the troposphere, polar latitude - descending air is transported into the polar lower stratosphere, where it accumulates.
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QBO – mechanisms
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Equatorially trapped Kelvin waves provide the westerly momentum and Rossby-gravity waves provide easterly momentum and these effects combine to produce the QBO oscillation.
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Brewer-Dobson circulation – dehydration
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Dehydration can occur by condensation and precipitation as a result of cooling to temperatures below -80°C. The lowest values of water are found just near the tropical tropopause.
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Polar vortex
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A persistent, large-scale cyclone located near one or both of a planet's geographical poles. On Earth, the polar vortices are located in the middle and upper troposphere and the stratosphere. They surround the polar highs and are part of the polar front. More stable in Antarctic than in Arctic due to landmass distribution.
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Brewer-Dobson circulation – transport of ozone and trace gases
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This type of circulation explains observed high ozone concentrations in the lower stratosphere polar regions, far from the photochemical source region in the tropical middle stratosphere; also explains north-south distributions of long lived constituents like nitrous oxide and methane.
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SSW
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Stratospheric sudden warming: an event where the polar vortex of westerly (eastwards) winds in the Northern winter hemisphere abruptly (i.e. over the course of a few days) slows down or even reverses direction, accompanied by a rise of stratospheric temperature by several tens of kelvins
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QBO – definition
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Equatorial Quasi-Biennial Oscillation; a long-term oscillation that overwhelms the seasonal cycle of zonal mean winds in equatorial stratosphere (below 35 km); not directly linked to the march of the seasons, somewhat irregular period (averaging 27 months),
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Water's unusual properties – cohesion
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means molecules stick to one another, leads to surface tension. Water's surface tension is highest, affects precipitaiton and cell biology
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QBO – mechanisms
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Equatorially trapped Kelvin waves provide the westerly momentum and Rossby-gravity waves provide easterly momentum and these effects combine to produce the QBO oscillation.
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Polar vortex
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A persistent, large-scale cyclone located near one or both of a planet's geographical poles. On Earth, the polar vortices are located in the middle and upper troposphere and the stratosphere. They surround the polar highs and are part of the polar front. More stable in Antarctic than in Arctic due to landmass distribution.
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Water's unusual properties – adhesion
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means water sticks to other stuff, leads to wetting
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SSW
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Stratospheric sudden warming: an event where the polar vortex of westerly (eastwards) winds in the Northern winter hemisphere abruptly (i.e. over the course of a few days) slows down or even reverses direction, accompanied by a rise of stratospheric temperature by several tens of kelvins
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Water's unusual properties – state
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exists in all 3 states at earth's surface
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Water's unusual properties – dissolving
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dissolves more substances in greater quantities than any other common liquid, crucial to chemical, biological and physical processes.
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Water's unusual properties – cohesion
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means molecules stick to one another, leads to surface tension. Water's surface tension is highest, affects precipitaiton and cell biology
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Water's unusual properties – adhesion
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means water sticks to other stuff, leads to wetting
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Water's unusual properties – density
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affected by temperature, salinity, and pressure; controls oceanic vertical circulation, seasonal stratification
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Water's unusual properties – state
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exists in all 3 states at earth's surface
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Water's unusual properties – heat capacity
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highest of all common solids and liquids, keeps climate on earth moderate
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Water's unusual properties – latent heat of vaporization
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highest of all common substances, major factor in heat transport in and btw ocean and atmosphere
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Water's unusual properties – dissolving
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dissolves more substances in greater quantities than any other common liquid, crucial to chemical, biological and physical processes.
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Water's unusual properties – density
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affected by temperature, salinity, and pressure; controls oceanic vertical circulation, seasonal stratification
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Waves – definition
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transfers a disturbance from one part of a material to another, propagated through the material without any substantial overall motion of the material itself, without any significant distortion of the wave form, and with constant speed.
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Wave motion
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A means whereby energy is transported across or through a material without any significant overall transport of the material itself.
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Water's unusual properties – heat capacity
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highest of all common solids and liquids, keeps climate on earth moderate
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Water's unusual properties – latent heat of vaporization
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highest of all common substances, major factor in heat transport in and btw ocean and atmosphere
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Wave dispersion
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Waves of different wavelengths become dispersed, because those with greater wavelengths and longer periods travel faster than smaller waves.
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Waves – definition
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transfers a disturbance from one part of a material to another, propagated through the material without any substantial overall motion of the material itself, without any significant distortion of the wave form, and with constant speed.
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Wave interactions
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If two wave trains of similar wavelength and amplitude travel over the same sea area, they interact. Where they are in phase, displacement is doubled, whereas where they are out of phase, displacement is zero.
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Wave motion
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A means whereby energy is transported across or through a material without any significant overall transport of the material itself.
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Wave group velocity
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Interacting waves produce wave trains, travelling as a series of wave groups, each separated from adjacent groups by an almost wave-free region. Wave group speed in deep water is half the wave (phase) speed. In shallowing water, wave speed approaches group speed, until they become equal.
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Wind waves
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Gravity waves formed by the transfer of wind energy into water; less than 3 meters high; wavelengths from 60 to 150 meters are most common in the open sea.
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Wave dispersion
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Waves of different wavelengths become dispersed, because those with greater wavelengths and longer periods travel faster than smaller waves.
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Tsunami
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Long-wavelength, shallow-water progressive waves caused by the rapid displacement of ocean water
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Wave interactions
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If two wave trains of similar wavelength and amplitude travel over the same sea area, they interact. Where they are in phase, displacement is doubled, whereas where they are out of phase, displacement is zero.
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Two theories of tides
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Equilibrium and dynamic
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Wave group velocity
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Interacting waves produce wave trains, travelling as a series of wave groups, each separated from adjacent groups by an almost wave-free region. Wave group speed in deep water is half the wave (phase) speed. In shallowing water, wave speed approaches group speed, until they become equal.
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Wind waves
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Gravity waves formed by the transfer of wind energy into water; less than 3 meters high; wavelengths from 60 to 150 meters are most common in the open sea.
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Equilibrium theory of tides
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basic theory of tides that examines the balance and effects of the forces that allow a planet to stay in a stable orbit. Assumes that the seafloor does not affect tides, and that ocean conforms instantly to forces that act on it.
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Dynamic theory of tides
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adds fluid motion dynamics to equilibrium theory; reconciles observations with predictions. Includes seabed contour, wave inertia, and water viscosity.
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Tsunami
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Long-wavelength, shallow-water progressive waves caused by the rapid displacement of ocean water
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Tidal frequencies
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diurnal, semidiurnal, mixed
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Two theories of tides
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Equilibrium and dynamic
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Equilibrium theory of tides
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basic theory of tides that examines the balance and effects of the forces that allow a planet to stay in a stable orbit. Assumes that the seafloor does not affect tides, and that ocean conforms instantly to forces that act on it.
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Tidal dissipation – how
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bottom friction especially in shallow seas, by the flow over seamounts and mid-ocean ridges, and by the generation of internal waves over seamounts and at the edges of continental shelves.
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Tidal dissipation – implications
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Tidal forces dissipate in the ocean, and much smaller amounts in the atmosphere and solid Earth. The dissipation increases the length of day by about 2.07 milliseconds per century, it causes the semimajor axis of moon's orbit to increase by 3.86cm/yr, and it mixes water masses in the ocean.
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Dynamic theory of tides
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adds fluid motion dynamics to equilibrium theory; reconciles observations with predictions. Includes seabed contour, wave inertia, and water viscosity.
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Surface currents – definition
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water flowing horizontally in the upper most 400 meters, driven mainly by wind friction, above the pycnocline. Transport heat.
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Tidal frequencies
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diurnal, semidiurnal, mixed
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Surface currents – pattern
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roughly reflects surface wind patterns
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Tidal dissipation – how
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bottom friction especially in shallow seas, by the flow over seamounts and mid-ocean ridges, and by the generation of internal waves over seamounts and at the edges of continental shelves.
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Ekman motion
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theoretical description of the motion of water affected by wind: effect of wind decreases with depth, and coriolis force deflects motion of the water away from direction of wind. Resulting pattern is an Ekman spiral.
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Tidal dissipation – implications
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Tidal forces dissipate in the ocean, and much smaller amounts in the atmosphere and solid Earth. The dissipation increases the length of day by about 2.07 milliseconds per century, it causes the semimajor axis of moon's orbit to increase by 3.86cm/yr, and it mixes water masses in the ocean.
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Surface currents – definition
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water flowing horizontally in the upper most 400 meters, driven mainly by wind friction, above the pycnocline. Transport heat.
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Ekman transport
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Total volume of water transported at right angles to the wind direction per second calculated by multiplying depth mean current speed by the thickness of the wind-driven layer.
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Ekman pumping
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upward movement of water in response to wind stress
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Surface currents – pattern
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roughly reflects surface wind patterns
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Intertial currents
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Rotational flows that continue after forces setting water in motion cease to act, influenced by Coriolis force. Water will continue to move until the energy supplied has been dissipated, mainly by internal friction.
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Ekman motion
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theoretical description of the motion of water affected by wind: effect of wind decreases with depth, and coriolis force deflects motion of the water away from direction of wind. Resulting pattern is an Ekman spiral.
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Geostrophic currents
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he currents that result when the horizontal pressure gradient force is balanced by the Coriolis force
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Ekman transport
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Total volume of water transported at right angles to the wind direction per second calculated by multiplying depth mean current speed by the thickness of the wind-driven layer.
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Ekman pumping
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upward movement of water in response to wind stress
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Dynamic topography
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Variations in the dynamic height of an isobaric surface
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Intertial currents
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Rotational flows that continue after forces setting water in motion cease to act, influenced by Coriolis force. Water will continue to move until the energy supplied has been dissipated, mainly by internal friction.
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Geoid
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The equipotential surface that corresponds to the sea-surface of a hypothetical motionless ocean.
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Geostrophic currents
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he currents that result when the horizontal pressure gradient force is balanced by the Coriolis force
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Dynamic topography
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Variations in the dynamic height of an isobaric surface
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Geoid
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The equipotential surface that corresponds to the sea-surface of a hypothetical motionless ocean.
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