World Geography / Climatology
Jet Streams in atmosphere occur near the altitudes of the Tropopause. Jet Streams have linear narrow meandering cores surrounded by quiet and calm weather.
They generally flow from West to the East. These are narrow linear pipe like structures and they run up to 500-1000 km in length and 100-200 m in diameter.
Within the Jet streams, winds are turbulent and fast, reaching up to 150-250 kmph. Their discovery was done by chance during the Second World War.
Types of Jet streams
There are mainly five types of jet streams that occur in the atmosphere.
- Subtropical Westerly Jet Streams ( in 300 – 350 latitude )
- Tropical Easterly Jet Streams ( in 100 – 200 latitude )
- Polar Front Jet Stream ( in 450 – 600 latitude ) ( strong during winter )
Above three Jet Streams are located within upper Troposphere ( 10-15km )
- Polar Night Jet Stream ( 100 latitude ) ( located in Stratosphere around 25km height )
- Somali Low Level Jet Stream ( 100 latitude ) ( located in lower Troposphere around 5km height )
Except in Tropical Easterly Jet Streams, the wind blows from West to East. All the Jet streams are permanent in nature, present
throughout the year except the Polar Night Jet Stream which is present only in the night.
Significance of Jet Streams
- Jet streams influence the weather at ground level. All Planetary, Secondary and Local winds are influenced by Jet streams. As an example, Monsoon is
influenced by different Jet streams.
- Somali Low Level Jet Stream ( Somalian coast to Kerala coast ) is sometimes strong and often weak. If it is strong, the Monsoon will be very active.
- Tropical Easterly Jet Streams strengthen the spread of Monsoonal winds over India.
- Subtropical Westerly Jet Streams control the onset of Monsoonal winds in India. If the Jet stream shifts to the North of Himalayas, there will be
onset of Monsoon in Kerala.
- Polar Front Jet Stream determines the temperate cyclones, which are steered by this Jet Stream.
- Polar Night Jet Stream controls the weather of the polar region.