7. Winds always blow from areas of higher pressure to areas of lower pressure. All else being equal, the shorter the distance (or the higher the pressure difference) between adjacent lows and highs, the stronger the wind.

Two factors control near-surface wind speeds: a) the pressure gradient and b) friction. The pressure gradient is the difference in pressure between two locations divided by their distance. The higher the pressure gradient, the stronger (faster) the wind. Friction, on the other hand, resists the movement of air molecules, and so acts to slow winds down. There are also two controls on wind direction: a) the Coriolis force (see below), and b) the relative locations of highs and lows (see No. 9).

Once anything moves on the rotating earth it is subjected to an apparent force that steers it to the right (clockwise - CW) of its intended path in the NH and to the left (counterclockwise - CCW) in the SH (Fig. 1). This is known as the Coriolis force (CF), or Coriolis effect, and is caused by the difference in the Earth's rotational speed at different latitudes.
 

Figure 1. Large scale winds are deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This deflection is due to the Coriolis effect.

The air that rises above equatorial regions and spreads poleward is turned by the CF so that it cools, grows heavy, and sinks in subtropical latitudes long before it reaches the poles. This creates areas of HP at the surface, which are the source of strong prevailing surface winds (i.e. the Trade Winds and Westerlies; Fig. 2).
 

Figure 2. The global atmospheric circulation set in motion by the heat of the sun and the rotation of the Earth produces latitudinal bands dominated by either high or low pressure, or by prevailing winds. These are the basic climatic zones of our planet.