Wind

Why air moves

Pressure Belts

Moving air

Wind is created by differences in air pressure The greater the difference, the faster the

wind moves The difference in air pressure is generally

caused by unequal heating of the earth Pressure differences at the equator and

the poles cause the air to move

Wind does not move in one huge circular patter from the pole to the equator

Smaller patterns called cells of rising and sinking air are present from the equator to the poles There are every 30° in both hemispheres

Coriolis Effect

Types of Winds

The curving of moving objects by the Earth’s rotationNorthern Hemisphere: Curves to right

Southern Hemisphere: Curves to left

Example: sharpie on rotating balloon

http://www.classzone.com/books/earth_science/terc/content/visualizations/es1904/es1904page01.cfm

Two main typesLocal WindsGlobal Winds

Trade Winds

Westerlies

The winds that blow from 30° latitude to the equator Curving of the trade winds are caused

by the Coriolis effect

This is the type of wind that effects the weather in KS Wind belts found in both Northern and

Southern Hemispheres between 30°-60° latitude

Flow toward the poles in opposite direction of the trade winds

Helped early traders return to Europe

Polar Easterlies

Jet Streams

The wind belts that extend from the poles to 60° latitude in both hemispheres Formed from cold, sinking air moving

from poles to 60° N & S.

Narrow belts of high-speed winds that blow in the upper troposphere and lower stratosphere Often change speed and can reach a

maximum speed of 500 mph Do not follow regular path around the

Earth Controls the movement of storms http://squall.sfsu.edu/crws/jetstream.h

tml

http://home.znet.com/aringler/jet.htm

Local Winds

Sea and Land Breezes

Winds influenced by the geography of an area Mountain or ocean breezes can

produce temperature differences that cause local winds

During the day, the land heats up faster than the water. This heats the air above it, pulling the cool air toward land

At night, the land cools faster than the water. This causes the cool air to flow out to the ocean.