Tropical areas receive more heat from the sun than do polar regions. The tropical atmosphere is hotter than the atmosphere in other areas. As a result the warm tropical air moves toward the poles. This starts a global movement, or circulation, of air. The global air movement has a great deal to do with what man does on Earth.
Oceans too receive differing amounts of heat.
This results in the flow of water masses which move continuously through the Earth's oceans. The Earth not only receives heat as radiation from the sun, but it also radiates heat back into space. Therefore a mammoth heat balance is maintained between the sun and the Earth. This balance keeps the Earth from getting so hot or so cold that life could not exist. The amount of heat from the sun that falls on a region determines the temperature range of the region.