What is it?
- Jet streams are strong, upper tropospheric flows that are quasi-horizontal in nature.
- They originate due to differential heating of the earth’s surface and form at the boundaries of adjacent air masses with significant temperature differences.
Characteristics of Jet Streams
- High-velocity winds- 400-500 km/hr.
- They cover hundreds of kilometres in width and thousands of km in length.
- Jet streams travel from west to east in both hemispheres.
- They have seasonal variations and shift with the apparent movement of the sun.
Types of Jet Streams
- Polar Front Jet Streams
- Formed above the convergence zone ( 40-60 degree) of surface polar cold air mass and tropical warm air mass.
- These move in easterly direction but are irregular.
- Subtropical Westerly Jet Streams
- Formed above 30-35 latitudes.
- Move in the upper troposphere to the north of the subtropical surface high-pressure belt.
- Tropical Easterly Jet streams
- Develop in the upper troposphere above surface easterly trade winds over India and Africa during the summer season due to intense heating of Tibetan plateau and play an important role in Indian Monsoon.
- Polar Night Jet Streams
- Develop in the winter season due to steep temperature gradients in the stratosphere around the poles.
