C. 22 Section 3 Atmospheric Circulation Air near Earth’s surface generally flows from the poles toward the equator.

Coriolis Effect  This affects the circulation of the atmosphere as well as the oceans.  When air moves toward the pole, it travels east faster than the land beneath it does—this equals a curved path.  Remember that the rotation of the Earth is what is causing the curve.

Winds blowing from high pressure to lower pressure areas curve due to Coriolis effect also.  Objects are deflected to the right in the Northern Hemisphere and are deflected to the left in the Southern Hemisphere.  The faster an object travels, the greater the Coriolis effect.

Global Winds  Winds that blow in one main direction are called prevailing winds.  Trade Winds are those that flow toward the equator between 30-0 degrees latitude. They are named from the direction they flow i.e. from the north = north trade winds.

What are the Westerlies?  The winds between degrees latitude that are flowing toward the poles but deflected by the Coriolis effect.  The westerlies blow thoughout the U.S.  Polar Easterlies are surface winds of high pressure by the 60 degree latitude pole area that are deflected by the Coriiolis effect and become the easterlies

Here are the wind patterns:

Doldrums  This is a narrow zone where the trade wind systems of the north and south hemispheres meet at the equator.

Horse Latitudes  Warm moist air heads upward and surface winds are weak and variable. Then the air approaches 30 degrees latitude, it comes down and a high- pressure zone forms.

Wind and Pressure Shifts  When the sun’s ray shift north or south as seasons change, so can the winds and pressure areas.  Jet streams-these are narrow bands of high-speed wind that blow in the upper troposphere and lower stratosphere.  Some are polar jet streams and also subtropical jet streams.

Polar jet stream

Subtropical jet stream

Local Winds  These are not part of the global wind belts.  The local conditions and temperatures are what influence local winds.  Breezes are gentle winds that extend over distances of less than 100 km.

Land and Sea Breezes  As the sun heats the land the warmed air rises and the cool air from the water area moves in to replace the warm water. This is a sea breeze because the air is moving from the sea into the land.  So what is a land breeze?

Land breeze:  During the night the land cools more rapidly than the water and a land breeze flows from the cool land toward the warmer water.

Mountain and Valley Breeze  Same thing—during the day a gentle breeze blows upslope because the air has been heated in the valley. This is the valley breeze.  At night, the mountains cool more quickly than the valley and a mountain breeze descends down the mountain (Remember cold air is more dense and sinks).

OKAY!!  Chapter 22 is complete!