Editing Jet stream (section)

{{short description|Fast-flowing atmospheric air current}}
{{Other uses}}
{{Distinguish|Jet (fluid)}}
{{Good article}}
{{Use dmy dates|date=February 2021}}
[[File:Aerial Superhighway.ogv|thumb|350px|The polar jet stream can travel at speeds greater than {{cvt|110|mph|km/h|order=flip}}. Here, the fastest winds are coloured red; slower winds are blue.]]
[[File:Straalstroom.jpg|thumb|250px|Clouds along a jet stream over [[Canada]].]]
{{Weather}}

'''Jet streams''' are fast flowing, narrow [[thermal wind|air current]]s in the Earth's [[Atmosphere of Earth|atmosphere]].<ref>{{Cite web |date=2021-02-24 |title=jet stream {{!}} National Geographic Society |work=National Geographic Society |url=https://www.nationalgeographic.org/encyclopedia/jet-stream/ |access-date=2023-07-03 |archive-date=24 February 2021 |archive-url=https://web.archive.org/web/20210224135823/https://www.nationalgeographic.org/encyclopedia/jet-stream/ |url-status=bot: unknown }}</ref>

The main jet streams are located near the altitude of the [[tropopause]] and are westerly winds, flowing west to east around the globe. The [[northern hemisphere]] and the [[southern hemisphere]] each have a '''polar jet''' around their respective [[polar vortex]] at around {{cvt|30000|ft|mi km}} above sea level and typically travelling at around {{cvt|110|mph|kph}} although often considerably faster.<ref name="rmets" /> Closer to the equator and somewhat higher and somewhat weaker is a '''subtropical jet'''.<ref name="rmets">{{cite web |title=Jet stream and stormy weather |url=https://www.rmets.org/metmatters/jet-stream-and-stormy-weather |last=McCabe |first=Kirsty |date=27 October 2022 |publisher=Royal Meteorological Society |access-date=2 December 2024}}</ref> 

The northern polar jet flows over the middle to northern latitudes of [[North America]], [[Europe]], and [[Asia]] and their intervening [[ocean]]s, while the southern hemisphere polar jet mostly circles [[Antarctica]].<ref>{{cite web |title=2024 Antarctic MERRA-2 Wind |url=https://ozonewatch.gsfc.nasa.gov/meteorology/wind_2024_MERRA2_SH.html |publisher=NASA |access-date=2 December 2024}}</ref> Jet streams may start, stop, split into two or more parts, combine into one stream, or flow in various directions including opposite to the direction of the remainder of the jet.<ref>{{cite book |title=A Dictionary of Aviation |first=David W. |last=Wragg |isbn=9780850451634 |edition=first |publisher=Osprey |year=1973 |page=168}}</ref> 

The [[El Niño–Southern Oscillation]] affects the location of the jet streams, which in turn affects the weather over the tropical [[Pacific Ocean]] and affects the climate of much of the [[tropics]] and [[subtropics]], and can affect weather in higher-latitude regions. The term "jet stream" is also applied to some other winds at varying levels in the atmosphere, some global (such as the higher-level polar-night jet), some local (such as the [[African easterly jet]]). Meteorologists use the location of some of the jet streams as an aid in [[weather forecasting]].  Airlines use them to reduce some flight times and fuel consumption. Scientists have considered whether the jet streams might be harnessed for power generation. In [[World War II]], the Japanese used the jet stream to carry [[Fu-Go balloon bomb]]s across the Pacific Ocean to launch small attacks on North America.

Jet streams have been detected in the atmospheres of Venus, Jupiter, Saturn, Uranus, and Neptune.<ref>{{Cite web |author1=Jeremy Hsu |date=2008-10-17 |title=One Mystery of Jet Streams Explained |url=https://www.space.com/5991-mystery-jet-streams-explained.html |access-date=2023-07-03 |website=Space.com |language=en |archive-date=3 July 2023 |archive-url=https://web.archive.org/web/20230703044924/https://www.space.com/5991-mystery-jet-streams-explained.html |url-status=live }}</ref>