APES Unit 4 Global Wind Patterns

Global Circulation currents

warm air at the equator rises

cold air at the poles sink

why can’t air move straight?

Coriolis effect

the earth is rotating and the air is spinning

albedo

percentage of incoming sunlight reflected from a surface

high = more reflected, less absorbed, cooler

* this applies on the earth for areas covered in snow, poles

low = more absorbed, less reflected, warmer

* tropical regions with dense green foliage

adiabatic cooling and heating

adiabatic cooling

as warm air rises, its pressure decreases and expands, lowering the temperature of the air

adiabatic warming

that cold air in the higher atmosphere then sinks back to the earth, decreasing in volume, and warming up

latent heat release

sun heats up water and it evaporates

when water vapor condenses into liquid water, it’s released as heat

latent heat release = energy released when water vapor in the atmosphere condenses to liquid

atmospheric convection currents

contributes to different global climates

global patterns of air movement

initiated by the unequal heating of the earth

hadley cell

air at equator tropics warms expands and rises

rising air cools, reaches saturation point, condenses, and falls as rainwater → latent heat release

in troposphere, adiabatic cooling occurs, the cold air is displaced north and south of the equator

sinking air is heated by adiabatic heating

this is why just north and south of the equator are deserts

the warm, dry air flows back to the equator

ITCZ intertropical Convergence Zone

latitude of most intense sunlight, causes the ascending parts of the hadley cells to converge

polar cells

located at the poles

air rises a little bit away from the pole and sinks @ pole

rising air cools, water vapor condenses, precipitates

air dries as it reaches the poles and sinks

then travels back out to 60 degrees N/S and completes the cycle

Ferrell Cells

not as distinct convection cells

driven by circulation of hadley and polar cells

warm air from the hadley cell moves towards the poles

cold air from the polar cell moves toward the equator

contributes to global circulation cells

coriolis effect

deflection of objects that are moving north or south due to the earth’s rotation

trade winds

air is moving really really fast at the equator

as the earth spins to the east, the wind is dragged to the west

polar easterlies

move in the same direction as the trade winds, to the west

polar cell, air circulates from 60 degrees to 90 degrees

air is moving faster at 60 degrees and deflected to the west

westerlies

air is moving from the equator to the poles, but because of the coriolis effect the path is diverted

deflected to the east