Cap 11 Upper Wind

Question 1

Thermal wind

Answer 1

Temperature influence on vertical pressure change.
Cold air pressure reduces quickly
Warm air pressure reduces slowly

Question 2

Jet stream

Answer 2

Jetstream are thermal wind

Question 3

Jetstream

Answer 3

Very strong upper winds are called jet stream.
Wind speed greater than 60kts and upto 350kts(rare).
At the equator is westerly direction.
Dimension: 2nm deep,200nm across,2000nm long
Ratio 1:100:1000

Question 4

Permanent jet stream and seasonal jet stream

Answer 4

Permanent:

Sub tropical jet&raquo_space;40000ft 150kts 30-40N
Subtropical jet»40000ft 80-90 kts. 30-40S
Polar fron jet»30000ft 150-200kts. 50-60 N

Seasonal
Tropical easterly jetstream» 50000ft july 90 kts 10-20n
Arctic fron jet»january 20000ft 80kts

Question 5

Crossing above and blowe Jetstream

Answer 5

Below the JS core, temperature colder when flying into the polare air from tropical air

Above the JS core,temperature warmer when flying towards polare air from tropical air

Question 6

Surface projection of jetstream

Answer 6

Jetstream appears as if it lies in the cold air when projected on to the surface due to the sloping temperature divion

Answer 7

The Polar fron jet stream lies closer to the cold front (50-200nm) than to the warm front
At the cold front the PFJ wind direction backs compared to the gradientwind (NH)
At the warm front the PFJ wind direction veers compared to the gradient wind.

Deduction: in the warm front the gradient wind keeps veering from surface to friction layer (3000ft) to the jet stream
In the cold front the gradient wind veers from surface to friction layer and then it backs to the jet stream

Answer 8

Polar front depression pfd

Question 9

Most dangerous cat

Answer 9

Strongest CAT near cold side below the jet core

Side of the warm sector facing the cold front

Answer 10

Only Jet streams above 80 kts are displayed on the chart

Wind arrow s indicated the level and location of the max wind speed core

Answer 11

Two horizontal double line indicated change of 20kts or 3000ft of the jetstream.

Question 12

Low level jetstream

Answer 12

Low level jet stream are narrow strong winds (approx 70 kts)
Located between 500 and 5000ft .often several hundred miles long.

Main Types:
~Nocturnal jet
~Valley inversion
~Coastal jet
~Ahead of cold front
~stationary front