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

With the Jet stream often looping to the north of the UK, large areas of high pressure dominated.

From BBC • Apr. 1, 2025

Jet stream patterns have a big impact on the weather.

From National Geographic • Jan. 26, 2024

Jet stream energy from the previous day was moving off to the northeast, over New England.

From Washington Post • Sep. 17, 2021

Jet stream speeds can occasionally top 150 mph.

From Seattle Times • Feb. 17, 2020

Jet stream or not, the balloon would have moved rapidly south, still climbing.

From The Report on Unidentified Flying Objects by Ruppelt, Edward J.