Wind

Wind The Earth is in a constant battle to equalize its temperature It never succeeds, because our planet is hotter in some places than in others

Wind Patterns Earth’s air is always on the move Cool air sinks Warm air rises Forms convection currents

Wind Wind is the movement of air as a result of different air pressure The greater the pressure difference, the stronger the wind Caused by unequal heating of the Earth

Pressure Belts

Coriolis effect Global winds do not blow in straight lines Coriolis Animation Global winds do not blow in straight lines The earth rotates as wind blows, making it seem as if the winds are curving Called the Coriolis effect

Coriolis Effect The wind blows in a curved path due to the rotation of the Earth Northern Hemisphere - winds curve to the right Southern Hemisphere - winds curve to the left Coriolis Effect Winds and the Coriolis Effect

Kinds of Winds Local winds- generally move short distances and can blow from any direction Global winds- are part of a pattern of air flow that moves across the Earth

Local Winds Land breezes and sea breezes occur because of the differences in heat of the land and the water These differences create a convection current

Air Cools Down Cold Air Sinks Wind Blows Toward Coast Warm Air Rises Sea Breeze During the day, the land heats up more quickly than the sea. Above the land, warm air rises and the wind blows toward the coast. Warm Air Rises Cold Air Sinks Air Cools Down Wind Blows Away from the Coast Land Breeze At night, the land cools down quickly while the sea stays warm. Above the sea, warm air rises and the wind blows away from the coast.

During the Day

At Night

L L H H Local Ocean Effects Sea Breeze happens during the day when the land heats up more than the ocean Land Breeze happens during the night when the land cools off more than the ocean

Global Wind Patterns Winds carry heat north from Earth’s equator Winds carry colder air south toward the equator

Global Winds Coriolis and other factors combine to produce a pattern of wind belts around the earth Major wind belts: Trade winds Westerlies Easterlies

Trade Winds Blow at 30* latitude to the equator. (early sailors used the winds to sail from Europe to America) When cold air sinks, produces high pressure High pressure wants to move to an area of low pressure--the equator!! These winds that are blowing toward the equator are deflected west because of the coriolis effect

Westerlies Between 30* and 60* latitude Flows towards the poles Helped ships return to Europe. Turned toward the east by Coriolils effect Blow from west to east-- WESTERLIES

Easterlies Between the poles and 60* latitude. Cold air near poles sinks and flows back toward lower latitudes Coriolis shifts these winds to west Wind goes from East to west-- EASTERLIES

Columbus and Global Scale Winds Columbus was an expert sailor with a extraordinary knowledge of the global winds. He did not attempt to sail into the teeth of the westerly winds, but rather turned south and used the Easterly Trade Winds to drive his ships across the Ocean. On the return voyage, he headed north and then used the westerlies to propel his ships back to Europe, stopping at the Azores on the way for much needed repairs.

Doldrums Near equator, between 0-30 degrees latitude Rising air, low pressure Cool air moves into area, warmed rapidly, and rises Warms so fast, air doesn’t have an opportunity to move very far before it rises again. Winds very weak near equator- DOLDRUMS

Doldrums All in a hot and copper sky, The bloody Sun, at noon, Right up above the mast did stand, No bigger than the Moon. Day after day, day after day, We stuck, nor breath nor motion; As idle as a painted ship Upon a painted ocean. - The Ancient Mariner

Horse Latitudes Between about 30° to 35° north and 30° to 35° south Latitude and Precipitation Between about 30° to 35° north and 30° to 35° south Weak winds Forms a belt of calm air Contributes to deserts in this area

Prevailing Wind Patterns

Global Wind Pattern Global Wind Patterns

Rainforests of the World Most rainforests are near the equator because this is where the air is rising, creating clouds and rain.

Deserts of the World Most deserts are at 30o N and S Latitude because the air is sinking, drying it out.

MoreDirect Sun Hot 0 o Equator 30 o S 60 o S 90 o S 30 o N 60 o N