Polar front jet stream
Topic: Atmospheric Pressure, Winds and General Circulation · NCERT: Beyond NCERT
Meaning
The polar front jet stream is a narrow band of very fast westerly wind, about 9–12 km up. It lies roughly between 40° and 60° latitude, above the polar front, where cold polar air meets warmer air. Sharp temperature contrast creates it, so it is strongest in winter. Its path winds in big loops. It steers temperate cyclones (mid-latitude storms) along its route. When it dips towards the equator, it lets cold polar air spread south.
Example
When this jet dips far south over North America in winter, Arctic air reaches deep into the United States and brings sudden cold outbreaks.
Don't confuse with
- Subtropical westerly jet stream: it flows higher (12–14 km) and nearer 30°. In winter it splits around Tibet, and its southern branch steers western disturbances over north India.
Related concepts
- Jet stream
- Subtropical westerly jet stream
- Tropical easterly jet stream
- Somali jet
- Rossby waves
- Polar vortex