jet stream

mixture of gases which are expelled from a jet engine with great force and which propel the aircraft forward

Jet streams are fast flowing, relatively narrow air currents found in the atmosphere at around 11 kilometers (36,000 ft) above the surface of the Earth. They form at the boundaries of adjacent air masses with significant differences in temperature, such as of the polar region and the warmer air to the south. The jet stream is mainly found in the tropopause, at the transition between the troposphere (where temperature decreases with height) and the stratosphere (where temperature increases with height).
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Noun
1. a high-speed high-altitude airstream blowing from west to east near the top of the troposphere; has important effects of the formation of weather fronts
(hypernym) airstream

n. jet stream, mixture of gases which are expelled from a jet engine with great force and which propel the aircraft forward

A migrating stream of high-speed winds present at high altitudes. (FAA4)