Wind

Wind is movement of air in the atmosphere. This movement is mostly caused by sunlight heating the gound, water and air, and by the effects of the rotation of the earth. Without solar heating, the air would rotate against the earth's rotation, due to the drag of the solar wind.

Due to differences in latitude, the planet's axial tilt, and the reflection and absorption of different materials and gases, some parts of the Earth get more energy than others, and they also have different capacities for holding on to that heat. Hot air expands, and that expansion causes the air to have a lower density. Colder air, with a higher density, will tend to displace warmer air by moving in under it. Since cold air holds less water vapor, there is often rain at the boundaries, or weather fronts, between air masses at different temperatures.

Over large bodies of water near the equator, monsoons and typhoons form, driven by the heat of the underlying water.

Patterns in winds around the world have long been known, both as semi-permanent phenomena, such as the jet streams, which are primarily rotational effects, and periodical occurrences, such as the shifting of the trade winds in the tropics and such seasonal winds as the cirocco.

Wind is imperative to sailing. Windmills also use the energy of wind, either directly (as to grind grain) or to generate electricity.

See also: meteorology, windstorm, horse latitude

In ancient Greek mythology, the four winds were personified as gods. Roman writers later gave them Latin names.

                      Greek        Latin
north wind            Boreas       Aquilo
south wind            Notus        Auster
east wind             Eurus
west wind             Zephyrus     Favonius
north-north west wind              Thrascius       
west-south-west wind               Libs
north-west wind                    Caurus or Corus
south-east wind                    Volturnus
south-west wind                    Africus or Afer ventus