Persistent winds which rise in the torrid and lower temperate zones and blow steadily towards the equator, being deflected westwardly by the earth's rotation, so that they become northeast or southeast winds, as they are north or south of the equator. They are caused by the ascent of heated air in the equatorial region, and the inflow of colder air to take its place. The ascending air outflows to the north and south and gradually descends to the surface, making what are known as anti-trade winds. The trades diverge to the north or south as the sun does so in its annual round.