Geog Exam 2

Front 1

air pressure

Back 1

the pressure produced by the motion, size, and number of gas molecules and exerted on surfaces in contact with the air; can be measured by mercury or aneroid barometer.

Front 2

mercury barometer

Back 2

a device that measures air pressure with a column of mercury in a tube that is inserted in a vessel of mercury

Front 3

aneroid barometer

Back 3

a device to measure air pressure using a partially emptied, sealed cell

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wind

Back 4

the horizontal movement of air relative to Earth's surface; produced essentially by air pressure differences from place to place; also influenced by the Coriolis force and surface friction. Turbulence adds wind updrafts and downdrafts and a vertical component to this definition

Front 5

anemometer

Back 5

a device to measure wind speed (velocity)

Front 6

wind vane

Back 6

a weather instrument used to determine wind direction; winds are named for the direction from which they originate

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pressure gradient force

Back 7

A force that causes air to move from areas of high barometric pressure (more dense air) to areas of lower barometric (less dense air)pressure due to pressure differences, causing winds. Without pressure gradient force, there would be no wind.

Front 8

Coriolis force

Back 8

A deflective force, makes wind that travels in a straight path appear to be deflected in relation to Earth's rotating surface. Deflects wind to the right in the Northern Hemisphere and to the left in Southern Hemisphere. Without Coriolis force, winds would move along straight paths between high- and low-pressure areas.

Front 9

friction force

Back 9

Drags on the wind as it moves across surfaces; it decreases with height above the surface. Without friction, winds would simply move in paths parallel to isobars and at high rates of speed.

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isobar

Back 10

an isoline connecting all points of equal pressure

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geostrophic wind

Back 11

Wind moving between pressure areas along a path parallel to isobars. In the upper troposphere, the pressure gradient force equals Coriolis force, so the amount of deflection is proportional to air movement.

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anticyclone

Back 12

A dynamically or thermally caused area of high atmospheric pressure with descending and diverging air flows that rotate clockwise in the Northern Hemisphere, and counterclockwise in the Southern Hemisphere

Front 13

cyclone

Back 13

A dynamically or thermally caused area of low atmospheric pressure with converging and ascending air flows that rotate counterclockwise in the Northern Hemisphere, and clockwise in the Southern Hemisphere.

Front 14

equatorial low-pressure through

Back 14

a thermally cause low-pressure area that almost girdles the Earth, with air converging and ascending all along it extent; also called intertropical convergence zone. Also called intertropical convergence zone

Front 15

polar high-pressure cell

Back 15

a weak, anticyclonic, thermally produced pressure system positioned roughly above each pole

Front 16

subtropical high-pressure cell

Back 16

a dynamically high-pressure area; found converging roughly the region from 20-35 degrees in both the north and the south latitudes; responsible for the hot, dry areas of Earth's arid semiarid deserts.

Front 17

subpolar low-pressure cell

Back 17

A region of low pressure centered approximately 60 degrees latitude in the North Atlantic near Iceland and in the North Pacific near the Aleutians, as well as in the Southern Hemisphere. Air flow is cyclonic; it weakens in summer and strengthens in winter.

Front 18

trade winds

Back 18

North east and southeast winds that converge in the equatorial low-pressure through, forming the intertropical convergence zone.

Front 19

westerlies

Back 19

The predominant wind-flow pattern from the subtropics to the hi latitudes in both hemispheres

Front 20

polar front

Back 20

A significant zone of contrast between cold and warm air masses; roughly situated between 50-60 degrees North and South latitude

Front 21

polar easterlies

Back 21

A variable, weak, cold, and dry wind moving away from the polar region; an anticyclone circulation

Front 22

Antarctic high

Back 22

A consistent high-pressure region centered over Antarctica; source region for an intense polar air mass that is dry and associated with the lowest temperatures on earth

Front 23

constant isobaric surface

Back 23

And elevated surface in the atmosphere on which all points have the same pressure, usually 500mb. Along this constant-pressure surface, isobars mark the paths of upper air winds

Front 24

Rossby wave

Back 24

An undulating motion in the upper air westerly circulation at middle and high latitudes

Front 25

jet stream

Back 25

The most prominent movement in upper level westerly wind flows; irregular, concentrated, sinuous bands of geostrophic wind, traveling at 300 km/h (190mph)

Front 26

land and sea breezes

Back 26

The wind along coastlines an adjoining interior areas created by different heating characteristics of land and water surfaces; onshore (landward) breeze in the afternoon and offshore (seaward) breeze at night

Front 27

Mountain and valley breezes

Back 27

A light wind produced as cooler mountain air flows downslope at night and as warmer Valley air flows upslope during the day

Front 28

katabatic winds

Back 28

Air drainage from elevated regions, flowing as a gravity wind. Layers of air at the surface cool, become denser, and flow downslope; known worldwide by any names

Front 29

monsoon

Back 29

From the Arabic word mausim, meaning "season"; refers to the annual cycle of dryness and wetness, with seasonally shifting winds produced by changing atmospheric pressure systems; affects India, Southeast Asia, Indonesia, northern Australia, and portions of Africa

Front 30

western intensification

Back 30

The piling up of ocean water along the western margin of each basin, to height of about 15 cm (6in); produced by the trade winds that drive the oceans westward in a concentrated channel

Front 31

upwelling current

Back 31

Ocean currents cause surface waters to be swept away from the coast by surface divergence or offshore winds. Cool, deep waters, which are generally nutrient rich, rise to replace the vacating water.

Front 32

downwelling current

Back 32

An area of the sea where a convergence or accumulation of water thrusts excess water downward, occurring, for example, at the western end of the equatorial current or along the margins of Antarctica

Front 33

thermohaline circulation

Back 33

Differences in temperature and salinity produced density differences important to the flow of deep, sometimes vertical, currents. Traveling at slower speeds than wind-driven surfaces currents, the thermohaline circulation hauls larger volumes of water.

Front 34

phase change

Back 34

The change in phase, or state, among ice, water, and water vapor; involves the absorption or release of latent heat

Front 35

sublimination

Back 35

A process in which ice evaporates directly to water vapor or water vapor freezes to ice

Front 36

latent heat

Back 36

The heat energy that is absorbed or released in the phase change of water and is stored in one of the three states; ice, water, or vapor; includes The latent heat of melting, freezing, vaporization, evaporation, and condensation.

Front 37

latent heat vaporization

Back 37

The heat energy that is absorbed from the environment in a phase change from liquid to water vapor at the boiling point; under normal sea-level pressure, 540 cal must be added to each gram of boiling water to achieve a phase change to water vapor.

Front 38

latent heat condensation

Back 38

The heat energy that is released in a phase change from water vapor to a liquid; 585 cal are released from 1 g of water vapor that condenses at 20 degrees C (68°F)

Front 39

latent heat evaporation

Back 39

The heat energy that is required to change phase from liquid to water vapor; under normal sea level pressure, 585 cal must be added to 1 g of water at (20 degrees C or 60 degrees F) to achieve a phase change to water vapor

Front 40

humidity

Back 40

The water vapor content of the air. The capacity of the air to absorb water vapor is mostly a function of the water vapor temperature and air temperature.

Front 41

relative humidity

Back 41

The ratio of water vapor actually in the air (content) compared to the maximum water vapor possible (capacity) at that temperature ( expressed as a percentage.

Front 42

saturation

Back 42

The condition of air that is holding all the water vapor that it can hold at a given temperature

Front 43

dew-point temperature

Back 43

The temperature at which a given mass of air becomes saturated, absorbing all the water it can. Any further cooling or addition of water vapor results in active condensation.

Front 44

vapor pressure

Back 44

That portion of total air pressure that results from water vapor molecules; expressed in millibars(mb). At a given temperature, the maximum capacity of the air is termed it saturation vapor pressure.

Front 45

specific humidity

Back 45

The mass of water vapor (in grams) per-unit mass of air (in kilograms) at any specific temperature. The maximum mass of water vapor that a kilogram of air can hold any specific temperature is termed the maximum specific humidity.

Front 46

stability

Back 46

The condition of a parcel (a body of air with a specific temperature and humidity, perhaps 300 m, 1000 feet, in diameter), weather remains where it is or changes its initial position. The parcel is stable if it resists displacement upward; it is unstable if it continues to rise.

Front 47

normal lapse rate

Back 47

The average rate of temperature decrease with increasing altitude in the lower atmosphere; an average value of 6.4 degrees C per km, or 1000 m (3.4 degrees F per 1000 ft).

Front 48

environmental lapse rate

Back 48

The actual lapse rate in the lower atmosphere at any particular time under local weather conditions; May deviate above or below the average normal lapse rate of 6.4 degrees C per 1000 m.

Front 49

adiabatic

Back 49

Pertaining to the heating and cooling of a descending or ascending parcel of air through compression and expansion, without any exchange of heat between the parcel and the surrounding environment.

Front 50

dry adiabatic rate

Back 50

The rate at which a parcel of air that is less then saturated cools (if ascending) or heats (if descending); a rate of 10 degrees C per 1000 m (5.5 degrees F per 1000 ft)

Front 51

moist adiabatic rate

Back 51

The rate at which a parcel of saturated air cools in ascent; rat of 6 degrees C per 1000 m (3.3 degrees F per 1000ft)

Front 52

cloud

Back 52

An aggradation of moisture droplets and ice crystals that are suspended in air and are great enough in volume and density to be visible; Basic forms include stratiform, cumuliform, and cirroform

Front 53

moisture droplet

Back 53

The initial composition of clouds; each droplet measures approximately 0.002 cm (0.0008 inches) in diameter and is invisible to the human eye

Front 54

condensation nuclei

Back 54

Necessary microscopic particles on which water vapor condenses to form moisture droplets; can be sea salts, dust, soot, or ash

Front 55

stratus

Back 55

A stratiform (flat, horizontal) cloud generally below 2000 m (6500 feet)

Front 56

nimbostratus

Back 56

A rain-producing, dark, grayish stratiform cloud characterized by gentle drizzles

Front 57

cumulus

Back 57

A bright puffy cumuliform cloud up to 2000 m (6500 feet) in altitude

Front 58

stratocumulus

Back 58

A lumpy, grayish, low-level cloud, patchy with sky visible; sometimes present at the end of the day.

Front 59

altocumulus

Back 59

Mid-level, puffy clouds that occur in several forms; patchy rows, wave patterns, a "mackerel sky", or lens-shaped "lenticular" clouds.

Front 60

cirrus

Back 60

Wispy filaments of ice crystal clouds that occur above 6000 m (20,000 feet); they appear in a variety of forms, from feathery hairlike fibers to veils of fused sheets.

Front 61

cumulonimbus

Back 61

A towering, precipitation producing cumulus cloud that is vertically developed across altitudes associated with other clouds; frequently associated with lightning and thunder and thus sometimes termed a thunderhead.

Front 62

fog

Back 62

A cloud, generally stratiform, in contact with the ground, with visibility usually restricted to less than 1 km (3300 feet).

Front 63

advection fog

Back 63

The active condensation formed when warm, moist air moves laterally over cooler water and land surfaces, causing the lower layers of the overlying air to be chilled to the dewpoint temperature.

Front 64

evaporation fog

Back 64

A fog formed when cold air flows over the warm surface of a lake, ocean, or other body of water as the water molecules evaporate from water surface into the cold, overlaying air; also known as a steam fog or sea smoke

Front 65

upslope fog

Back 65

The fog that forms when moist air is forced to higher elevations along a hill or mountain and is thus cold

Front 66

valley fog

Back 66

The settling of cooler, more dense air in low-lying areas, which produces saturated conditions and fog

Front 67

radiation fog

Back 67

A fog formed by a radiative cooling of the surface, especially on clear nights in areas of moist ground; occurs when the air layer directly above the surface is chilled to the dewpoint temperature, thereby producing saturated conditions.

Front 68

air mass

Back 68

A distinctive, homogeneous body of air in terms of temperature and humidity that takes on the moisture and temperature characteristics of its source region

Front 69

convergent lifting

Back 69

Air flows in conflict force lifting and displacement of air upward, initiating adiabatic process.

Front 70

convectional lifting

Back 70

Air passing over warm surfaces gains buoyancy and lifts, initiating adiabatic processes

Front 71

orographic lifting

Back 71

The uplift of migration air masses in response to the physical presence of a mountain, a topographic barrier. The lifted air cools adiabatically as it moves upslope and may form clouds and produce increased precipitation.

Front 72

rain shadow

Back 72

The area on the leeward slopes of a mountain range, in the shadow of the mountains, where precipitation receipt is greatly reduced compared to that of windward slopes.

Front 73

cold front

Back 73

The leading edge of a cold air mass; identified on a weather map as a line marked with a series of triangular spikes pointing in the direction of frontal movement

Front 74

warm front

Back 74

The leading edge of an advancing warm air mass that is unable push cooler, passive air out of the way; tends to push the cooler, underlying air into a wedge shape; noted on weather maps with a series of rounded knobs placed along the front in the direction of the frontal movement

Front 75

squall line

Back 75

A zone slightly ahead of a fast-advancing cold front, where wind patterns are rapidly changing and blustery and precipitation is strong

Front 76

lightening

Back 76

A flash of light caused by tens of millions of volts of electrical charge igniting the air to temperatures of 15,000-30,000 degrees C

Front 77

thunder

Back 77

The violent expansion of suddenly heated air, created by lightning discharges, sending out shockwaves as an audible sonic bang.

Front 78

hail

Back 78

A type of precipitation formed when a raindrop is repeatedly circulated above and below the freezing level in a cloud, with each cycle adding more ice to the hailstone until it becomes to heavy to stay loft

Front 79

derecho

Back 79

A strong linear wind in excess of 26 m/s (58 mph) associated with thunderstorms and bands of shower crossing a region

Front 80

mesocyclone

Back 80

A large, rotating circulation initiated within a parent cumulonimbus cloud at the mid-troposphere level; generally produces heavy rain, large hail, blustery winds, and lightning; may lead to tornado activity

Front 81

funnel cloud

Back 81

The visible swirl extending from the bottom side of a cloud, which may or may not develop a tornado. A tornado is a funnel cloud that has extended all the way to the ground.

Front 82

tornado

Back 82

An intense, destructive cyclonic rotation, developed in response to extremely low pressure; associated with mesocyclone.

Front 83

waterspout

Back 83

An elongated, funnel shaped circulation formed when a tornado takes place over water

Front 84

tropical cyclone/ hurricane/ typhoon

Back 84

A cyclonic circulation originating in the tropics, with winds between 30-64 knots (39-73 mph; 63-118 km/h); characterized by closed isobars, circular organization, and heavy rains.