It has been harnessed for over one thousand years to pump water, to grind grain and to provide motive power for other activities. Wind is the product of the movement of air. Air has a certain density and surrounds the earth for a layer of approximately 64km in altitude. Air exerts a downward pressure, which is referred to as atmospheric pressure.
Air pressure is measured with a barometer.
However, the air higher up is less affected. The difference between the speed at which air moves close to the surface and the speed of air higher up forms vortexes or whirlpools. Additionally, the sun warms the earth and the atmosphere. Heating is greater at the equator than at the earth's poles. Warm air rises while cold air sinks.