Wind is simply air in motion. It is caused by the sun’s uneven
heating of the Earths surface: This happens when the Earth s
surface which is made of different types of land and water,
absorbs the sun s heat at different rates. The presence of
clouds can also locally reduce the effectiveness of the sun’s
rays. During the day, the air above the land heats up faster
than the air over water. The warm air over the land expands and
rises up in the atmosphere, and the heavier, cooler air rushes
in to take its place, creating winds. At night, the small-scale
winds are reversed because the air is getting cool more rapidly
over land than over water. In the same way, the large scale
atmospheric winds that circle the Earth are created because the
land and sea near the earth’s equator is heated more by the sun
than the land and sea near the North and South Poles. The use of
the wind as a prime mover ceased only in the 20th Century, the
age when coal and conventional liquid fuels were expanding
rapidly and electricity was