weather term
Jet Stream
A narrow band of fast-moving air high in the atmosphere that steers weather systems across the mid-latitudes.
Jet streams form where large temperature differences meet, typically between polar and tropical air masses, and can reach speeds well over 200 km/h. The position and strength of the jet stream has a huge influence on day-to-day weather: a jet stream that dips further south than usual can drag colder air with it, while a jet stream running further north often means a milder, wetter pattern for places in its southern flank.