The weather is a complex system and a number of factors influence it. Chief among them are the rotation of the planet which helps give direction to the winds. This disturbance in the atmosphere takes the form of a giant heat exchange system with hot air moving from the tropics to the poles and cold air moving from the polar regions towards the Equator. These movements help to balance the overall temperature of the Earth. Otherwise the tropics would become unbearably hot and the middle latitudes increasingly cold.

The sea gains and gives up heat more slowly than the land. The ocean currents are dependent on the winds themselves and influence the winds helping to carry heat to the colder parts of the Earth. The winds also carry the life-giving rain on which human activities like agriculture depend. The El Ni