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How is wind caused?

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Wind is caused by air flowing from areas of high pressure to areas of low pressure. Since the Earth is rotating, however, the air does not flow directly from high to low pressure, but it is deflected to the right (in the Northern Hemisphere; to the left in the Southern Hemisphere), so that the wind flows around the high and low pressure areas. This effect of the wind "feeling the Earth turn underneath it" is important for very large and long-lived pressure systems. For small, short-lived systems (such as in the cold outflow of a thunderstorm) the wind will flow directly from high pressure to low pressure.

The closer the high and low pressure areas are together, the stronger the "pressure gradient", and the stronger the winds. On weather maps, lines of constant pressure are drawn (as in the example, above) which are called "isobars". These isobars are usually labeled with their pressure value in millibars (mb). The closer these lines are together, the stronger the wind. The curvature of the isobars is also important to the wind speed. Given the same pressure gradient (isobar spacing), if they are curved anticyclonically (around the high pressure in the above example) the wind will be stronger. If the isobars are curved cyclonically (around the low pressure in the example above) the wind will be weaker.

Near the surface of the Earth, friction from the ground slows the wind down. During the day, when convective mixing is stirring up the lower atmosphere, this effect is minimized. At night, however, when convective mixing has stopped, the surface wind can slow considerably, or even stop altogether.

Wind can also be thought of one way that the atmosphere moves excess heat around. All wind is, directly or indirectly, helping to transport heat either away from the surface of the Earth, where sunlight causes an excess of energy buildup, or from warm regions (usually the tropics) to cooler regions (usually the higher latitudes). Etraatropical cyclones accomplish much of this heat transport outside of the tropics, while in the tropics the trade winds, monsoons and hurricanes transport much of the heat.
Here are some interesting facts. World record wind speed: The highest wind speed ever recorded on the surface of the Earth was 231 mph on April 12 1934, atop Mt. Washington, New Hampshire. This high-elevation weather station experienced the winds of an extremely strong jet stream that had descended unusually low in the atmosphere. The wind affects the earth's rotation: During the northern hemisphere winter, the stronger westerly winds that build up in the Northern Hemisphere, combined with frictional drag at the Earth's surface, actually produce a very small, but measurable, increase in the speed of rotation of earth.
Generally, wind occurs due to temperature differentials between different areas. For example, different areas will absorb the sun's heat differently causing a temperature differential, e.g., the equator is hotter than the north or south pole. The cooler air of the poles sinks and the warmer air at the equator rises causing a natural flow. Rotation of the earth also contributes to wind - while the pole-equator flow is going on, the earth is turning underneath the air.

Local temperature differentials also cause wind flow, e.g., between sea and land.
Wind is created by the air flowing from a high pressure area to a low pressure area. Interestingly, the direction is influenced by the rotation of the earth.

Wind is caused by the pressure gradient force, which arises from the uneven heating of earth's surface. Once it is in motion, the Coriolis force arises from Earth's rotation to deflect it (right in the northern hemisphere, left in the southern hemisphere). Or, in simple language, heat from the sun warms the Earth's atmosphere. This causes the air to rise. Wind is the cold air 'rushing in' to fill the 'space' left.

Detailed Answer
Differing levels of heat on the surface of earth is the main cause of wind, also the spin of the earth adds a small amount of winds and the orbiting pull of the moon causes some winds (even more the tides.) Wind is air movement so anything moving on the earth can cause wind, just on a very small scale. Saturn is a neat example for winds - it's a gas planet so it's very light, the atmosphere can get winds of up to 600mph. Part of this is heat from the sun, part again from spin, even more is caused by the 10+ moons it has.

Heat input varies by season, cloud cover, latitude, and surface conditions, ocean surfaces heat and cool slowly, Land heats and cools quickly...

This all combines to affect overall air pressure. When one area heats up the air pressure rises, and the higher pressure air expands and tries to diffuse into the lower pressure areas. And vice versa. Warmed air also rises, while cooling air sinks.

These effects cause air to start moving relative to the earth's surface. As air moves around the earth's surface it crosses areas that are moving either faster or slower than the air. Close to the pole, the Earth and air over it are moving much slower, than are the air and earth at the equator. Air moving outward from the axis or inward toward the axis has a different angular momentum that the area it is moving into. This is called the coriolis effect and it results in air moving in cyclonic patterns. The effect is relatively mild at the equator- but gains in strength as you move toward the poles and thus closer to the axis of rotation. This is why hurricanes become more forceful as they move away from the equatorial regions. Air in a High pressure zone flows outward, dissipating its energy, resulting in calm weather. But air flowing into a low pressure zone is concentrating its energy into a smaller space. Thus low pressure zones cause generally higher winds and stronger cyclones.
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What causes wind chill?

When the wind is blowing it increases the rate of evaporation ofmoisture from our skin. The evaporation absorbs heat, making itfeel colder.

What causes the reversal of monsoons winds?

Hot weather in the summers warms up the plateau and causes vaporization in the sea as well. Winds continuously travel from land to sea and back thus forming low pressures on t

Do the sun cause wind?

No the sun does not. Yes, it is the "wind" from the sun that causes the aurora borealis here on earth and pushes the tails of comets away from the sun.
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What is wind and what causes it?

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