Chapter 11 - Upper Winds and the Jet Steam

Question 1

What is the minimum speed for a jet stream?

Answer 1

60kts

Question 2

What is the maximum speed of a jet stream?

Answer 2

Approximately 300 - 400 kts

Question 3

What is the typical speed range for jet streams?

Answer 3

Between 150 - 180 kts

Question 4

Will a jet stream be in the cold or warm air in a front?

Answer 4

The warm air.

Question 5

What is clear air turbulence and where can it be found?

Answer 5

The rapid change in wind speed and/or direction. It is often found around a jet stream or around CBs and thunderstorms.

Question 6

Where will the worst turbulence be around a jet stream?

Answer 6

On the side with the cold front but still in the warm air.

Question 7

What is the length, width and depth of a typical jet stream?

Answer 7

2000 miles long, 200miles wide and 2 miles deep.

Question 8

When is CAT most prounounced around a jet stream?

Answer 8

When the jet stream changes direction and on the cold side.

Question 9

Approximately, how high is the arctic jet stream? (winter only)

Answer 9

20000ft

Question 10

Approximately, how high is the polar jet stream?

Answer 10

30000ft

Question 11

Approximately, how high is the subtropical jet stream?

Answer 11

40000ft

Question 12

Approximately, how high is the equatorial jet stream? (NH summer only)

Answer 12

50000ft

Question 13

Approximately, how high is the polar night jet stream? (70deg N/S, winter only)

Answer 13

70000ft

Question 14

What units do contour/thickness charts use?

Answer 14

decameters (10s of meters)

Question 15

Which jet stream is easterly and when does it occur and why?

Answer 15

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.

Question 16

Why do jet streams occur?

Answer 16

Due to the huge temperature gradients between fronts creating geostrophic winds of very high speeds.

Question 17

What is the broad formation of jet streams on the earth not including the equatorial jet stream or arctic jet stream?

Answer 17

See figure.

Question 18

How does temperature change across the core of a jet stream?

Answer 18

It doesnt, it is approximately constant.

Question 19

What does the Buys Ballots law state?

Answer 19

In the NH, with your back to the wind the low pressure/temperature/height is on your left.

Question 20

What are upper winds mostly dependant on?

Answer 20

Temperature.