Global winds and air masses, illustration. In the tropics, the winds flow from east to west and are known as the tropical easterlies or trade winds. At higher latitudes, the winds flow from west to east and are called prevailing westerlies. Where these two winds diverge, at 30 degrees latitude, areas of high pressure form known as the horse latitudes (red). They are characterised by sunny skies, calm winds and little precipitation. In the polar regions, cooler air flows back towards lower latitudes and are known as the polar easterlies. Where these winds diverge, at 60 degrees latitude, with the westerlies areas of low pressure form. There is a strong temperature gradient that can lead to the formation of extratropical cyclones that bring winds and precipitation. For a labelled version of this image see C057/3846.