JETSTREAM ?WHAT IS MEAN

Jet stream : Is a strong wind ,narrow current on a quasi-horizontal axis in the upper tropopause or stratosphere layers , characterized by strong vertical and horizontal windshear ( CAT ), the wind speed is greater than 60 knots for a wind to be classified as Jetstream

Jet stream are 1500NM long ,200 NM wide and 12000ft deep and their is directly proportional  to the thermal gradient

note : the greater the thermal gradient , the greater is the speed of the Jetsream .

WHAT IS THE ( CAT ) CLEAR AIR TURBULENCE?

CAT :  there is no signs of visible moisture content in turbulent air .

what cause the  CAT ? 

1-LOW LEVEL CAT  : caused by

a- Temperature inversion

b-a difference between the surface and gradient wind due to the turbulent mixing of boundary layer near the surface .

c- local surface winds ( sea or land breezes )

d- terrain wind 

High level CAT 

2- Jetstream : the most sever CAT can be found level or above the jet core in warm air mass and on the cold air polar side of the jet 

3- Fronts : produce a marked horizontal windshear which can produce CAT .

4-Thunderstorms : CAT windshear can be found at low level under the thunderstorm ; microbursts .

5- Wake turbulence