full text of the classic FAA guide
Differences in temperature create differences in pressure. These pressure differences drive a complex system of winds in a never ending attempt to reach equilibrium. Wind also transports water vapor and spreads fog, clouds, and precipitation. To help you relate wind to pressure patterns and the movement of weather systems, this chapter explains convection and the pressure gradient force, describes the effects of the Coriolis and frictional forces, relates convection and these forces to the general circulation, discusses local and small-scale wind systems, introduces you to wind shear, and associates wind with weather.