Winds

Local and Global

Wind: The Basics

Wind is the horizontal movement of air from a high pressure area to a lower one. Differences in air pressure, often caused by the unequal heating of Earth's surface, cause wind. There are two types of main winds, local winds, and global winds.

Local Winds

Local winds blow over short distances. They are caused by the unequal heating near lakes and coastlines. The land heats more quickly than the water, causing different temperatures to occur. There are two types of local winds, sea breezes, and land breezes.

Sea Breezes

Sea breezes are the winds that blow from a body of watertowards land. They are usually around during the day, when the descending cool air sweeps over the water, sending the surface air towards land. The warm air on land then rises and returns towards the water. This happens because the land heats faster than the water.

Land Breeze

Land breezes are the winds that blow from land towards a body of water. They usually occur overnight, when the descending cold air sweeps over the land, sending surface air towards the water. The warm air on land then rises, and returns to the land. This happens because water holds heat longer than land.
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Global Winds

Global winds are caused by widespread, uneven heating of the Earth's surface. Warm air rises at the equator and sinks at the poles, causing higher pressure at the equator and low pressure at the poles. Surface winds then blow towards the poles, and the result is global wind.

There are 6 types of global winds, but I will be focusing on 4: doldrums, polar easterlies, jet streams, and prevailing westerlies.

Doldrums

Doldrums are generally calm areas with extremely weak winds. They are located on the equator (0 degrees latitude).

Polar Easterlies

Polar easterlies are winds that blow towards the southwest from the north pole and northwest from the south pole.

Prevailing Westerlies

Prevailing westerlies blow from the west. They make their way towards the both polar easterlies. Prevailing westerlies are located in between 30 and 60 degrees latitude in both the north and the south hemispheres.

Jet Streams

Jet streams are wide bands of high speed winds about 12 km above the ground. These winds are extremely strong, and can travel at over 200 km per hour. There are usually 4 jet streams, 2 in the northern hemisphere and 2 in the southern hemisphere.