Fast and Consistent
Wind is the movement of air caused by the uneven heating of the Earth's atmosphere. As the Earth orbits the sun, it is bombarded with solar radiation. This radiation strikes the Earth’s equator more directly than polar areas resulting in great temperature variations. Generally, wind occurs because of these radiation differences. For example, the equator is hotter than the north or south pole. The cooler air of the poles sinks and the warmer air at the equator rises causing a natural flow.
Due to the Earth’s rotation, air moving within this current does not travel in a straight line, instead curves over the surface. It is this deflection that results in the lateral wind movements we are familiar with -- e.g. the prevailing westerlies, northeasterly and southeasterly trades. These lateral movements also result in not one, but three, circulation cells wherein air is continually warming and cooling, ascending and descending. Areas of low-pressure cool air and high-pressure warm air define these cells, and it is at these intersections of differing pressures that jet streams occur.