jet stream

American  

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.

---

jet stream British  

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

---

jet stream Scientific  

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.

---

jet stream Cultural  

1. A narrow band of swiftly moving air found at very high altitudes.

---

Discover More

Movements of the jet stream have important (but generally short-lived) effects on weather patterns.

Travel time in an airplane can be lengthened or shortened by the jet stream, depending on the direction of flight and the strength of the stream.

Etymology

Origin of jet stream

First recorded in 1945–50

Example Sentences

“We were standing in the jet stream, on the edge of space,” Whittaker wrote in his 1999 memoir, “A Life on the Edge.”

From Los Angeles Times • Apr. 8, 2026

"Just as small shifts in the jet stream can change the weather, small changes in these cellular winds could change how diseases begin or progress," Cathy said.

From Science Daily • Apr. 1, 2026

Dips in the jet stream will allow arctic air to spread across the UK by the end of the UK.

From BBC • Mar. 9, 2026

Cold Arctic air, transported south over North America by the polar jet stream in the winter, meets warmer air over the Atlantic Ocean and the Gulf.

From The Wall Street Journal • Feb. 23, 2026

Thrust high into the jet stream, the mountain ripped a visible gash in the 120- knot hurricane, sending forth a plume of ice crystals that trailed to the east like a long silk scarf.

From "Into Thin Air" by Jon Krakauer