33 terms

WEATHER AND CLIMATE

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ADVECTION FOG
Active condensation formed when warm moist air moves laterally over land surfaces, causing lower layers of air to be chilled to the dew point temperatures.
ALTITUDE
Angular distance between the horizon (horizontal planes) and the sun.
ALTOSTRATUS
Middle clouds that appear bluish-grey, never white due to high amoun t of condensed water vapour in the cloud.
ANEMOMETER
Device that measure wind velocity.
ANTICYCLONE
Areas of high pressure with descending and divergin air flows that rotate clockwise in the northern hemisphere, and counter clockwise in the south hemisphere.
ASPECT
Angle of the mid-day sun; direct exposure.
BAROMETER
Instrument measuring air pressure.
CHINOOK
Warm, dry, downslope of air flow; characteristic of the rain shadow region on the leeward side of mountain.
CIRRUS
Wispy, filamentous, ice-crystal cloud, feathery hair-like, highest visible clouds
CUMULONIMBUS
Towering, percipitation-producing cumulus cloud that vertically develops across altitudes associated with other clouds, lightening and thunder produced
CUMULUS
Vertical clouds, often white in color with dark flat base. RIsing air currents produce cauliflower appearance. May be transformed into cumulonimbus with extreme heating in atmosphere.
CYCLONES
Areas of low atmospheric pressure.
FRONTAL/CYCLONIC PERCIPITATION
Occurs when 2 air masses meet; warmer air will be forced to rise and clouds and rain will result.
HURRICANES
Develop over warm oceans due to great amount of water vapour, usually associated with equatorial air masses.
MONSOON WINDS
Annual cycle of dryness and wetness with seasonally shifting winds produced by changing atmospheric pressure system. Affects India, southeast Asia, Indonesia, Northern Australia. Seasonal wind reverals caused by the differential heating of the land masses and water bodies.
NIMBOSTRATUS
Rain producing low cloud, dark, grey clouds characterized by light drizzle.
OCCLUDED FRONT
Overrunning of a surface warm front by a cold front and the subsequent lifting of the warm air wedge off the ground; moderate- heavy percipitation.
RADIATION FOG
Formed by radioactive cooling of a land surface, especially on clear nights in areas of moist ground; occurs when air layer above surface is chilled to the dew point temperature, producing saturated conditions.
RAINSHADOW
Area on the leeward slope of mountain range where percipitation is greatly reduced compared to the wind ward slope on the other side.
TORNADOES
Develop around intense low pressure, associated with massive thunder storms that develop along fronts between warm tropical and cool polar air masses.
PRESSURE GRADIENT
Change in air pressure as one moves from one location to another.
HEAT ISLAND
Increased temperatures found in the center of large urban areas compared with surrounding of rural suburban areas.
CONTINENTAL POLAR
Very cold, stable, and dry air mass, dense so air mass stays in contact with ground, clear sunny skies and high pressure
MARITIME POLAR
Cool, moist, unstable air mass
MARITIME TROPICAL
Warmer and more stable than maritaim polar, sunny skies and winter percipitation
CONTINENTAL TROPICAL
Very hot and dry conditions
ADIABATIC COOLING
When air is forced to rise, the air pressure decreases with elevation and the air begins to expand. As the air expands, it loses heat, resulting in a form of cooling known as:
ADIABATIC HEATING
As the air reaches the summit and begins to descend into the valley on the leeward side, it warms, contracts, and pressure increases as elevation decreases. This warming phase is called:
CONVECTIONAL PERCIPITATION
Rainfall occurs in tropical regions and over large land masses. The sun heats the ground, which heats the atmosphere causing the heated air to rise. As the air rises, cooling takes pleace forcing the temperature to reach dewpoint. The clouds develop vertically, towering cumulonimbus clouds produce short, sudden downpours.
ABSOLUTE HUMIDITY
Amount of water vapour in a given volume of air. (highest at the equator)
RELATIVE HUMIDITY
The percentage of the amount of water that air can hold at a given temperature.
EL NINO
Refers to the displacement of an upwelling of cold ocean water with much warmer surface waters.
LA NINO
Opposite of El nino; cools ocean temperatures.