Ocean currents play a very crucial role as regulators of the thermal environment at the earth’s surface. When we consider the entire globe, the vast current systems are much helpful in the exchange of heat between the low and high latitudes.

Thus, they are so essential in sustaining the terrestrial energy budget. However, even on a local scale warm ocean currents bring a moderating influence to coasts in Polar Regions. On the other hand, cool currents greatly reduce the heat of tropical deserts along narrow coastal belts.

Where a warm ocean current flows near a coast, temperatures tend to be moderated. It is the result of the moderation of temperature affected by the Gulf Stream and the North Atlantic Drift that the British Isles and the northwestern Europe have the mild climate.

On the contrary, where winds coming from over the warm water blow over the cooler land, there are heavy cloud cover and frequent precipitation.

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Where there is a cool current offshore, it tends to induce cooler temperatures over the adjacent land than might otherwise be expected. In such a case, the amount of precipitation is reduced.

This is because a stable lapse rate or even a temperature inversion produced in the lower troposphere results from such a cool offshore, current.

Besides, if there is a cool current in combination with the descending air of high-pressure system, the result is an extremely dry coastal climate as is found in Chile, Peru and southwest Africa.

When moisture-laden winds blowing towards land come into contact with the cool waters of the ocean currents and the lower temperatures that they have, they lose much of their moisture through the process of condensation.

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This condensed moisture usually takes the form of fog. However, when such an air passes over the warm land, its moisture holding capacity is increased. Thus, there is little chance of precipitation.