What Is A Jet Stream?

Meteorologists explain their major effects on the weather and flights.
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Probing Question: What is the jet stream?

Penn State Department of Meteorology - Images of the jet stream

Paul G. Knight

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Jet stream - Air currents that move west to east; used by meteorologists for weather forecasting and by pilots to reduce the length of airplane flights.

Origin: Jet streams are caused by the Earth's rotation and heating from the sun.

During airplane flights :  Pilots can reach their destinations sooner by flying with the jet stream and use more fuel when they have to fly against it. The jet stream is believed to be the cause of a form of turbulence that occurs in clear air.