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Posted by on Sep 7, 2015 in Tell Me Why |

How Fast Can Winds Blow?

How Fast Can Winds Blow?

In the United States, most winds average eight or twelve miles an hour near the ground. At this speed, papers blow along the ground and leaves rustle in trees. Large windstorms called hurricanes have winds blowing at 74 miles per hour or higher. High in the sky, in the top part of the stratosphere, winds can blow up to 350 mph. Scientists call these winds the jet stream.

Tornadoes have the strongest winds on Earth. They whirl around at more than 300 miles per hour. And in the center of the funnel, air can move as fast as a jet plane—500 mph.

Wind has the ability to pick up and transport small amounts of dust and rocks. Over time, the wind can completely change what a particular location looks like. Temperature differences can also affect how an area looks, both in the short term and in the long term.

Wind is the movement of air caused by the uneven heating of the Earth by the sun. It does not have much substance—you cannot see it or hold it—but you can feel its force. It can dry your clothes in summer and chill you to the bone in winter. It is strong enough to carry sailing ships across the ocean and rip huge trees from the ground.

It is the great equalizer of the atmosphere, transporting heat, moisture, pollutants, and dust great distances around the globe. Landforms, processes, and impacts of wind are called Aeolian landforms, processes, and impacts. Differences in atmospheric pressure generate winds.

At the Equator, the sun warms the water and land more than it does the rest of the globe. Warm equatorial air rises higher into the atmosphere and migrates toward the poles. This is a low-pressure system. At the same time, cooler, denser air moves over Earth’s surface toward the Equator to replace the heated air. This is a high-pressure system. Winds generally blow from high-pressure areas to low-pressure areas.

The boundary between these two areas is called a front. The complex relationships between fronts cause different types of wind and weather patterns.

Prevailing winds are winds that blow from a single direction over a specific area of the Earth. Areas where prevailing winds meet are called convergence zones. Generally, prevailing winds blow east-west rather than north-south. This happens because Earth’s rotation generates what is known as the Coriolis effect. The Coriolis effect makes wind systems twist counter-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.

The Coriolis effect causes some winds to travel along the edges of the high-pressure and low-pressure systems. These are called geostrophic winds. In 1857, Dutch meteorologist Christoph Buys Ballot formulated a law about geostrophic winds: When you stand with your back to the wind in the Northern Hemisphere, low pressure is always to your left. (In the Southern Hemisphere, low-pressure systems will be on your right.)

Content for this question contributed by John Stec, Jr., resident of Westfield, Hampden County, western Massachusetts, USA