Explain the reason for wind circulation on earth's surface
Answers
wind circulation is caused by two phenomenon.
1. uneven heating of land and water.
2. coriolis force produced dew to earth's rotation
The illustration below portrays the global wind belts, three in each hemisphere. Note that the U.S. lies primarily in the Westerly Wind Belt with prevailing winds from the west. Each of these wind belts represents a "cell" that circulates air through the atmosphere from the surface to high altitudes and back again. The cells on either side of the Equator are called Hadley cells and give rise to the Trade Winds at Earth's surface. How do we explain this pattern of global winds and how does it influence precipitation?
Global wind belts inculding hadley cells, mid-latitude cells, polar cells, polar easteries, polar front, westerlies, trade winds, and equatorial low winds
Figure 20. Global Winds
Source: NASA
We'll start at Earth's equator, where solar radiation is highest year around. Air near the equator is warmed, and rises because it is less dense (mass/unit volume) than the air around it as shown in Figure 21 below.
Solar radiation is pushed toward the equator and it then rises.
Figure 21. Air near the equator is heated and rises as indicated by the red arrows.
Source: Mike Arthur and Demian Saffer
The rising air creates a circulation cell, called a Hadley Cell, in which the air rises and cools at high altitudes moves outward (towards the poles) and, eventually, descends back to the surface. The continual heating and rise of air at the equator creates low pressure there, which causes air to move (wind) towards the equator to take the place of the air that rises. On the other hand, sinking air creates high pressure at the surface where it descends. A gradient of pressure (high to low) is formed that causes air to flow away from the high and towards the low pressure at the surface.