Weather and storm generation

The global heat engine

The Earth absorbs radiation from the sun while at the same time radiating energy into space at longer wavelengths. Near the equator, incoming radiant energy from the sun exceeds that emitted by the Earth and heats the tropical oceans and the atmosphere above them. Conversely, energy is lost from the polar regions where outgoing radiation emitted by the Earth exceeds the incoming solar energy. This uneven heating and cooling causes large-scale vertical and horizontal movements of air and water as the atmosphere and the oceans attempt to create a more uniform temperature distribution. These atmospheric and ocean currents are in turn affected by the rotation of the Earth, the distribution of continents and oceans, and the Earth's topography. In effect, the atmosphere and the oceans combine to operate as a vast heat engine, collecting and dispersing energy in a complex manner that involves both vertical and horizontal circulations in the atmospheric and oceanic fluids. Figure: Ocean heat transport in petawatts. Man's global energy consumption is about 0.016 petawatts. (A McDonald and C Wunsch)

The ocean weather factory

The world's oceans exert a major influence on global weather and climate through the exchanges of energy and moisture noted earlier and are, in effect, a giant factory for the production of tropical and extratropical storms, clouds, fog, land and sea breezes, and related phenomena. Tropical cyclones, also called hurricanes or typhoons depending on the geographical region, form over tropical waters, gaining their energy from the upward fluxes of heat and moisture from the ocean surface. Extratropical depressions of middle and high latitudes, in general, also either develop over the ocean or intensify there due to reduced frictional drag and the supply of heat and moisture from the water surface. Air masses are modified substantially as they pass over ocean waters. Warm moist air masses of tropical origin are cooled from below as they move poleward over colder water, producing fog and low cloud. Conversely, cold polar or arctic airmasses are heated and supplied with moisture as they push towards the equator over progressively warmer water. This process generates upward movement of parcels of air, or convection, which produces cloud and showers.
 

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