Origin of Wind

NWS - Wind is simply the air in motion. Usually when we are talking about the wind it is the horizontal motion we are concerned about. If you hear a forecast of west winds of 10 to 20 mph that means the horizontal winds will be 10 to 20 mph FROM the west.

Although we cannot actually see the air moving we can measure its motion by the force that it applies on objects. For example, on a windy day leaves rustling or trees swaying indicate that the wind is blowing. Officially, a wind vane measures the wind direction and an anemometer measures the wind speed.

The vertical component of the wind is typically very small (except in thunderstorm updrafts) compared to the horizontal component, but is very important for determining the day to day weather. Rising air will cool, often to saturation, and can lead to clouds and precipitation. Sinking air warms causing evaporation of clouds and thus fair weather.

Pressure gradient is the difference in pressure between high and low pressure areas. Wind speed is directly proportional to the pressure gradient. This means the strongest winds are in the areas where the pressure gradient is the greatest.