---
source: https://iinventedlight.com/library/notes/jet-stream.md
title: "What is the jet stream?"
license: CC-BY-4.0
license_url: https://creativecommons.org/licenses/by/4.0/
source_license: "US government work, public domain; restated in our own words"
attribution: "Summary by iinventedlight (AI-assisted). Sources: NOAA, The Jet Stream, US government work, public domain; NOAA, Global Atmospheric Circulations, US government work, public domain."
author: "iinventedlight (synthesis of cited sources); text drafted with AI assistance"
date: 2026-11-04
status: published
checked_on: 2026-11-04
as_of: 2026-11-04
confidence: medium
untested: "No observation or experiment was done; only the fetched government pages were read."
category: coverage-gaps
topic_area: "science-explain: weather and atmosphere"
tags: science, weather, jet-stream, atmosphere
sources:
  - id: S1
    title: "The Jet Stream"
    publisher: NOAA
    url: https://www.noaa.gov/jetstream/global/jet-stream
    accessed: 2026-11-04
    license: "US government work, public domain"
  - id: S2
    title: "Global Atmospheric Circulations"
    publisher: NOAA
    url: https://www.noaa.gov/jetstream/global/global-atmospheric-circulations
    accessed: 2026-11-04
    license: "US government work, public domain"
---
# What is the jet stream?

## Short answer
Jet streams are narrow bands of strong wind high in the atmosphere, usually around 30,000 feet. They blow from west to east but wander north and south because they follow the boundary between hot and cold air. [S1]

## Why they exist
They are part of global atmospheric circulation, the movement of air that carries heat and storms around the planet. Each hemisphere has three circulation cells; the Hadley cell near the equator lifts heated air and sends it poleward aloft. [S2]

## Claims
- id: C1
  claim: Jet streams are narrow bands of strong upper-level wind.
  source: S1
  evidence: "Jet streams are relatively narrow bands of strong wind in the upper levels"
- id: C2
  claim: Jet stream winds blow from west to east.
  source: S1
  evidence: "Within jet streams, the winds blow from west to east"
- id: C3
  claim: Global circulation moves heat and storms around the Earth.
  source: S2
  evidence: "It explains how thermal energy and storm systems move over the Earth's surface."
- id: C4
  claim: There are three circulation cells in each hemisphere.
  source: S2
  evidence: "there are three circulations in each"

## Sources
- [S1] The Jet Stream. NOAA. https://www.noaa.gov/jetstream/global/jet-stream . License: US government work, public domain. Accessed 2026-11-04.
- [S2] Global Atmospheric Circulations. NOAA. https://www.noaa.gov/jetstream/global/global-atmospheric-circulations . License: US government work, public domain. Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).