Chapter 11 - Upper Winds and the Jet Steam Flashcards
What is the minimum speed for a jet stream?
60kts
What is the maximum speed of a jet stream?
Approximately 300 - 400 kts
What is the typical speed range for jet streams?
Between 150 - 180 kts
Will a jet stream be in the cold or warm air in a front?
The warm air.
What is clear air turbulence and where can it be found?
The rapid change in wind speed and/or direction. It is often found around a jet stream or around CBs and thunderstorms.
Where will the worst turbulence be around a jet stream?
On the side with the cold front but still in the warm air.
What is the length, width and depth of a typical jet stream?
2000 miles long, 200miles wide and 2 miles deep.
When is CAT most prounounced around a jet stream?
When the jet stream changes direction and on the cold side.
Approximately, how high is the arctic jet stream? (winter only)
20000ft
Approximately, how high is the polar jet stream?
30000ft
Approximately, how high is the subtropical jet stream?
40000ft
Approximately, how high is the equatorial jet stream? (NH summer only)
50000ft
Approximately, how high is the polar night jet stream? (70deg N/S, winter only)
70000ft
What units do contour/thickness charts use?
decameters (10s of meters)
Which jet stream is easterly and when does it occur and why?
The equatorial jet stream, in summer because of the heating of land masses causing the indian subcontinent and the African west continent to be hotter than their relatively cooler oceans to the south. Thus creating a pressure difference a then a jet stream.
Why do jet streams occur?
Due to the huge temperature gradients between fronts creating geostrophic winds of very high speeds.
What is the broad formation of jet streams on the earth not including the equatorial jet stream or arctic jet stream?
See figure.
How does temperature change across the core of a jet stream?
It doesnt, it is approximately constant.
What does the Buys Ballots law state?
In the NH, with your back to the wind the low pressure/temperature/height is on your left.
What are upper winds mostly dependant on?
Temperature.
