The prevailing winds are the trends in speed and direction of wind over a particular point on the earth's surface. A region's prevailing winds often reflect global patterns of movement in the earth's atmosphere. Bold text For other uses, see Wind (disambiguation). ... This article is about Earth as a planet. ... “Air” redirects here. ...

Geostrophic winds

See also: Geostrophic wind

Effect of prevailing wind on a coniferous tree, western Turkey

The prevailing surface winds are calm at equator (the doldrums), then they blow from the northeast immediately north of the equator and from the southeast immediately south of the equator: these are called the trade winds because they allowed early European ships to sail from east to west to the Americas. Around 25 degrees north and south, near the tropics, the winds calm again in the horse latitudes. The geostrophic wind is defined as the wind resulting from the balance between the Coriolis force and the pressure gradient force. ... Image File history File linksMetadata Size of this preview: 305 × 599 pixelsFull resolution (1170 × 2297 pixel, file size: 332 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Prevailing winds Metadata This file contains... Image File history File linksMetadata Size of this preview: 305 × 599 pixelsFull resolution (1170 × 2297 pixel, file size: 332 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Prevailing winds Metadata This file contains... World map showing the equator in red In tourist areas, the equator is often marked on the sides of roads The equator marked as it crosses Ilhéu das Rolas, in São Tomé and Príncipe. ... The thunderstorms of the Intertropical Convergence Zone form a line across the eastern Pacific Ocean. ... The trade winds are a pattern of wind found in bands around Earths equatorial region. ... Horse latitudes or Subtropical High are subtropical latitudes between 30 and 35 degrees both north and south, characterized by light winds and hot, dry weather, caused by descending air. ...

Most of this activity is due to air pressure. At the equator, the heat causes air to rise, creating a belt of low pressure in the doldrums. After the air rises, it flows north and south high in the atmosphere until it cools enough to subside, creating belts of high pressure in the horse latitudes. All of that extra air has to go somewhere, so it blows towards the equator as the trade winds, and towards the middle latitudes as the prevailing westerlies. Air pressure can refer to: Atmospheric pressure, the pressure of air environmentally Pressure of air in a system Category: ... The middle latitudes are the areas between 30 and 60 degrees north latitude and 30 and 60 degrees south, or, roughly, the earths temperate zones between the tropics and the Arctic and Antarctic. ...

Meanwhile, at the poles, the cold causes air to subside, increasing the air pressure to cause the polar highs. As with the horse latitudes, the extra air has to flow somewhere, so it flows back in the direction of the equator as the polar easterlies, creating the far northern and southern climates of the world. The polar highs are areas of high atmospheric pressure around the north and south poles. ...

References

• Prevailing winds at Manchester Municipal University
• Prevailing winds and general circulation patterns at InfoPlease encyclopedia