jet stream

noun

1. strong, generally westerly winds concentrated in a relatively narrow and shallow stream in the upper troposphere of the earth.
2. similar strong winds in the atmosphere of another planet: jet streams on Jupiter.
3. the exhaust of a jet or rocket engine.

noun

1. meteorol a narrow belt of high-altitude winds (about 12 000 metres high) moving east at high speeds and having an important effect on frontogenesis
2. the jet of exhaust gases produced by a gas turbine, rocket motor, etc

1. A narrow current of strong wind circling the Earth from west to east at altitudes of about 11 to 13 km (7 to 8 mi) above sea level. There are usually four distinct jet streams, two each in the Northern and Southern hemispheres. Jet stream wind speeds average 56 km (34 mi) per hour in the summer and 120 km (74 mi) in the winter. They are caused by significant differences in the temperatures of adjacent air masses. These differences occur where cold, polar air meets warmer, equatorial air, especially in the latitudes of the westerlies.