Subpolar low
Topic: Atmospheric Pressure, Winds and General Circulation · NCERT: Class 11, Ch 9 "Atmospheric Circulation and Weather Systems"
Meaning
The subpolar lows are belts of low pressure near 60° N and 60° S. They are dynamic in origin, which means air movement causes them, not heating. Here the milder westerlies meet the cold polar easterlies along the polar front. The lighter air is forced to rise, which lowers the surface pressure. The rising air brings cloud, rain and frequent storms. Temperate cyclones form here.
Example
In the Northern Hemisphere the belt breaks into separate low-pressure cells. The Icelandic low lies over the North Atlantic near Iceland. The Aleutian low lies over the North Pacific near the Aleutian Islands. Both are known for stormy weather.
Don't confuse with
- Equatorial low: this is also a low-pressure belt, but it is thermal. Strong heating near the equator, at 0–5°, makes the air rise.
- Subtropical high: this is the high-pressure belt near 30°. The westerlies blow from it towards the subpolar low.