The horse latitudes are subtropical belts of high atmospheric pressure which lie over the oceans, between 30-35 degrees north, and 30-35 degrees south. They develop best over the oceans: the Southern Hemisphere has the larger belt, since it has more ocean. Because they contain dry and subsiding air, they produce arid climates in the land areas below them.
The name is thought to come from the practice of throwing horses overboard to conserve water, in the days of sailing ships, when ships were making too little progress within the belts of pressure.
