Lower limit is 60 kts

maximum speeds occur near the tropopause, 200 kts have been recorded in Europe/N Atlantic and 300 kts in Asia.

Speed along axis is not always uniform

there are distinct maxima it could be 60 kts or something else

Jet stream has strong horizontal and vertical wind share

vertical wind shear are 5m/s

Stronger as vertical wind shear is 5 m/s and , vertically 5 km of depth makes this speed stronger than horizontal which is 100 of km

The Speed of jet stream along the axis is not uniform it has distinct maxima it would be 60 ktshours or 200 kts

Along the axis of a jet stream there are centres of high speed winds, called Jet streaks (wind maxima), with weaker winds in between. Jet streaks retain their strength but move slower, by up to 25 kt, than the jet stream. In a wavy jet they are located over or near the ridge.

Al the jet stream except (TEJ )tropical easterly jet stream are westerly

°

In summer it moves north

in winter south

Sub-tropical Jet Stream
The STJ appears over the N India in October after the withdrawal of monsoon and shifts progressively southwards with the progress of the winter. Its mean position is roughly at 27? N at a height of 12 km. It reaches its southern most position of 22? N in February. STJ prevails over the Indian subcontinent for about eight months (Oct to May). After May it shifts northwards and moves out of the Indian subcontinent.

STJ has a layered structure. There are often two layers of maximum wind, to the S of the jet core. The jet stream strengthens by 10- 15 kt downstream, along the axis from Jodhpur to Guwahati.

STJ has a layered structure. There are often two layers of maximum wind, to the S of the jet core. The jet stream strengthens by 10- 15 kt downstream, along the axis from Jodhpur to Guwahati.

At the jet stream gradient is small, to the south it is high

Strong vertical wind shear is often concentrated just above and below the core it is greater above the core than below it

The tropical easterly jet stream is Seen over India from June to August and disappears by September

The strongest development of the jet is at about 15 kilometres (9 mi) above the Earth’s surface with wind speeds of up to 40 metres per second (140 km/h; 89 mph; 78 kn) over the Indian Ocean

RAINY EASON JULY-AUGUST

STJ are best developed in winter and early spring. Their maximum speed approaches 300 knots

TROPICAL EASTERLY JET STREAM HAVE A SPEED OF 80 KNOTS

HENCE LESS WIND SHEAR IN TEJ

Clouds. Jetstream has extensive sheets of high clouds on warm side, with sharply defined edges, usually parallel to the jet axis. CI clouds are more common on the cold side while CS and CC clouds on the warm side. On cold side cloud tops are invariably just below the tropopause whereas on the warm side tops are a few thousand feet below the tropopause. Roll type of CI or CS may be seen all along the length. Where moisture is less a thin layer of haze is noticed on the warm side and clear on the cold side.

Buys Ballot’s Law states that: If an observer stands with his back to the wind, the lower pressure is on his left in the northern hemisphere, and on his right in the southern hemisphere.

July – august