2nd atmosphere (geo. exam #2)

intertropical convergence zone

the zone where the air from the N and S hemis meet (close to the equator)

weak horizontal flow with feeble and erratic winds

shift is greater over land, than over sea

warm surface conditions, low pressure, high rainfall

rising air in the hadley cells creates instability

trade winds

cover most of the earth, between 25 degrees north and south latitude

prominent and consistent of oceans, general flow east to west

originate as warming, drying winds capable of holding an enormous amount of water — some of the world’s wettest places

subtropical highs

semiperm. high-pressure cell at about 30 degrees lat. at each ocean basin

develop from the descending air of the Hadley Cells

represent intensified cells of high pressure in two general ridges of high pressure (in each hemisphere)

weather is typically warm, dry, and calm (world’s major deserts)

westerlies

flow from west to east between 30-60 degrees N and S

less constant and persistent than trade winds

jet streams

polar front (westrerlies)

the jet is created by the convergence of cold air masses descending from the Arctic and rising warm air from the tropics

subtropical (westerlies)

relatively narrow bands of strong wind in the upper levels of the atmosphere

rossby waves (westerlies)

frequently sweeping undulations producing a meandering jet stream

wanders widely north and south

separate colder polar air from warmer tropical air

polar front (subpolar lows)

characterized by rising air, widespread cloudiness, precipitation, and stormy weather

polar easterlies

occupies most of the area between the polar highs and 60 degrees of latitude

winds move east to west

cold and dry, but variable

polar highs

high-pressure cells located over the polar regions

air from above sinks down into the high and diverges horizontally near the surface

forming the polar easterlies

anti-trade winds

blow from the southwest in the Northern Hemi

blow from the northwest in the Southern Hemi

flow eventually becomes more westerly

high-elevation poleward flow of air in the Hadley cell is deflected by the Coriolis effect

monsoons

the seasonal reversal of winds

mostly observed in southern and eastern Asia

onshore flow (monsoons)

sea-to-land movement in the summers

heavy rainfall

offshore flow (monsoons)

land-to-sea movement in the winters

dry season

sea breeze

from sea to land — during the daytime

rarely influential for more than 20-25km inland

caused by differential warming of land and water surfaces (low pressure system is created

land breeze

land to sea, occurs at night and is typically weaker than daytime winds

land and the air above it cool more quickly than the adjacent body of water

produces high pressure over land

valley breeze

during the day, conduction and radiation from the land surface cause air near the mountain slopes to warm more than air over the valley floor

warmed air rises creating a low pressure area

air from the valley floor flows upslope from high-pressure area to the mountain peak, prominent in summer

mountain breeze

at night, slopes lose warmth rapidly

chilled air then dips downslope

winter

katabatic winds (gravity-flow winds)

originate in cold highland areas, the cascade towards lower elevations due to gravity

air is dense and cold — warmed adiabatically as it descends

common in greenland and antartica

Foehn and Chinook Winds

originates when steep pressure gradient develops

high pressure on the windward side of a mountain

low pressure on the leeward side

air moves down the pressure gradient, from windward to leeward

Santa Ana Winds

develops when a cell of high pressure persists over the interior of the western USA for several days

wind diverges clockwise out of the high bringing dry warm winds to the coast

ideal conditions for wildfires

el nino

west coast of south america, equatorial pacific ocean

warm water appears at the surface of the ocean

replaces the cold, nutrient-rich water

2-7 years

la nina

water off South America becomes unusually cool

trade winds are stronger than usual

waters off Indonesia are unusually warm, SW USA is drier than usual

2-7 years