Wind

What causes wind? Differences in heat and pressure cause winds. Cold air is more dense and creates more pressure. Different parts of the Earth receive and absorb different amounts of heat. Wind helps distribute the heat more evenly.

Local Winds The most common local winds are sea and land breezes. A sea breeze occurs near coasts during the day. Land heats up more quickly than water, and warm air rising above the land pulls cool air in from the sea. The reverse happens at night. The land cools more rapidly, and warm air rising over the water pulls cool air in from the land.

Regional Winds The best know regional winds are monsoons. Monsoons work much like sea and land breezes, but on a larger scale. Instead of being driven by night and day warming, they are driven by summer and winter warming.

Global Winds Global winds are one part of Earth’s air conditioning. They move cold air from the poles toward the equator and warm tropical air toward the poles. They form into belts: the polar easterlies, prevailing westerlies, and trade winds. There are also calm belts known as the doldrums and horse latitudes.

The Coriolis Effect The Coriolis effect shapes global winds and cyclones. The Earth’s spin causes winds to curve to the right in the northern hemisphere, and to the left in the southern hemisphere. The Coriolis effect also shapes ocean currents.