Meteorology Chapter 4

Front 1

Know all processes of the hydrologic cycle:

Back 1

study the damn chart

Front 2

Know the unique qualities of water on Earth

Back 2

Water is the only liquid on the surface of the Earth in large quantities.

• It exists in all forms on Earth. (solid, liquid and gas)

• Ice (solid state) is less dense than liquid.

• Water has a high heat capacity.

• It has a unique ability to form hydrogen bonds

Front 3

What is a calorie?

Back 3

the heat necessary to raise the temperature of 1 gram of water 1 degree Celsius

Front 4

Evaporation

Back 4

Liquid is changed to gas

• 600 calories per gram of water are absorbed–

• A cooling process

Front 5

condensation

Back 5

Water vapor (gas) is changed to a liquid

• 600 calories per gram of water are released

• A warming process

Front 6

melting

Back 6

Solid is changed to a liquid

• 80 calories per gram of water are absorbed

• A cooling process

Front 7

Freezing

Back 7

Liquid is changed to a solid

• 80 calories per gram of water are released

• A warming process

Front 8

sublimation

Back 8

Solid is changed directly to a gas (e.g., ice cubes shrinking in a freezer)

• 680 calories per gram of water are released

• A warming process

Front 9

deposition

Back 9

Water vapor (gas) changed to a solid (e.g., frost in a freezer compartment)

• 680 calories per gram of water is absorbed

• A cooling process

Front 10

absolute humidity

Back 10

mass of water vapor in a given volume of air

Front 11

mass of water vapor in a unit of air compared to the remaining mass of dry air

Back 11

mixing ratio

Front 12

indicates how close the air is to saturation

Back 12

relative humidity

Front 13

Vapor capacity of air related to temperature

Back 13

warm air can hold more water vapor

Front 14

Stored or "hidden" heat not derived from temperature change.

Back 14

latent heat

Front 15

Relative humidity related to temperature

Back 15

lowering the temperature raises the relative humidity

Front 16

used to measure the humidity

Back 16

hygrometer

Front 17

What is a Psychrometer and how does it work

Back 17

compares temperatures of wetbulb thermometer and dry-bulb thermometer

• If the air is saturated (100% relative humidity) then both thermometers read the same temperature

• The greater the difference between the thermometer readings, the lower the relative humidity

Front 18

How do adiabatic temperature changes work (rising and sinking air)

How does this change relative humidity?

Back 18

Adiabatic temperature changes occur when

1. Air is compressed

• Descending air is compressed due to increasing air pressure

• Air will warm, relative humidity will decrease.

2. Air expands

• Rising air will expand due to decreasing air pressure

• Air will cool, relative humidity will rise

Front 19

note

Back 19

As air rises, it expands and cools until it hits its condensation limit and it creates clouds

Front 20

wet adiabatic rate

Back 20

• Commences at lifting condensation level

• Air has reached the dew point

• Condensation is occurring and latent heat is being liberated (released)

• Heat released by the condensing water reduces the rate of cooling

• Rate varies from 5˚C to 9˚C per kilometer

Front 21

occurs when elevated terrains, such as mountains, act as barriers to the flow of air.

Back 21

orographic lifting

Front 22

occurs where unequal surface heating causes pockets of air to rise because of their buoyancy

Back 22

Localized convective lifting

Front 23

where the air is flowing together and rising (low pressure)

Back 23

convergence

Front 24

frontal wedging

Back 24

Masses of warm and cold air collide, producing fronts.

• Cooler, denser air acts as a barrier over which the warmer, less dense air rises..

• Fronts are part of the storm systems called mid-latitude cyclones

Front 25

dry adiabatic rate

Back 25

Unsaturated air

• Rising air expands and cools at 10˚C per kilometer (5.5˚F per 1,000 feet)

• Descending air is compressed and warms at 10˚C per kilometer

• Descending air always warms at this rate

Front 26

Resists vertical displacement

• Cooler than surrounding air

• Denser than surrounding air

• Wants to sink (tendency)

• No adiabatic cooling

Back 26

stable air

Front 27

Instability is enhanced by the following:

Back 27

1. Intense warming of the lowest layer of the atmosphere by radiation

2. Heating of an air mass from below when passing over warm surface

3. General upward movement of air caused by orographic lifting, frontal wedging, and convergence

4. Radiation cooling from cloud tops

Front 28

Stability is enhanced by the following:

Back 28

1. Radiation cooling of Earth’s surface after sunset

2. Cooling of an air mass from below as it traverses cold surface

3. General subsidence (sinking) within an air column

Front 29

occurs when the environmental lapse rate is less than the wet adiabatic rate.

parcel is always cooler than surrounding air

Back 29

absolute stability

Front 30

Rising air

• Warmer than surrounding air

• Less dense than surrounding air

• Continues to rise until it reaches an altitude with the same temperature

• Adiabatic cooling

• Environmental lapse rate is greater than the dry adiabatic rate

• Clouds are often towering

Back 30

absolute instability

Front 31

occurs when the atmosphere is stable for an unsaturated parcel of air but unstable for a saturated parcel

• Dry adiabatic rate is cooler than the environmental lapse rate (stable)

• Wet adiabatic rate is warmer than the environmental lapse rate (unstable)

Back 31

conditional instability -

air is stable as it rises until it hits the dew point and cools slower, where it becomes very unstable

Front 32

In winter, air is rendered sufficiently unstable when cold, dry air passes over a warm, wet surface, which can often produce snow over the Great Lakes.

Back 32

lake effect

Front 33

a general, downward air flow.

• This results with stable air and clear, blue, cloudless skies.

Back 33

subsidence

Front 34

What is a temperature inversion and how can if affect air quality?

Back 34

a reversal of the lapse rate. This can lead to trapping of air pollutants and poor air quality

Front 35

Usually not effected by surrounding air.

Entrainment is mixing with surrounding air.

Back 35

air parcel

Front 36

parcels of air that rise similar to hot air balloons

Back 36

thermals

Front 37

Temperature to which a parcel of air would need to be cooled to reach saturation

• Cooling the air further causes condensation

Back 37

Dew point temperature

Front 38

the part of the total atmospheric pressure attributable to its water-vapor content

Back 38

vapor pressure