Upper Level Winds

Question 1

How do upper winds occur

Answer 1

TEMP difference creates a PRESSURE difference

Question 2

What direction are the winds in both hemispheres

Answer 2

WESTERLY at altitudes in the troposphere

Question 3

What is different in the stratosphere to do with temp

Answer 3

It is colder at the equator and less cold at the poles
Opposite

Question 4

What happens to winds at the equator during summer

Answer 4

They could be easterly over India or Africa

Question 5

What is a Jet Stream

Answer 5

A strong narrow current characterised by strong vertical or lateral wind shears where wind speed must exceed 60kt

Question 6

Why do jet streams occur at the polar tropopause and tropical tropopause boundaries

Answer 6

Because there is a steeper temperature gradient at these points

Question 7

What is normally the strongest jet stream

Answer 7

The polar front jet

Question 8

What are the two main jet streams

Answer 8

Polar front
Sub tropical

Question 9

What are the typical jet streams dimensions

Answer 9

2nm / 2000ft tall
200nm wide
1500nm + long

Question 10

What is the ratio or width to height of a jet stream

Answer 10

100 : 1

Question 11

What is the
Minimum
Typical
Less frequent
Rare
Speeds of a jet stream

Answer 11

61-80kt
100-150 kt
150 - 200 kt
More than 200kt

Question 12

What is the difference in earths spinning speeds at the equator and 30 latitude

Answer 12

Equator is 900kt
30 latitude 780 kt
Due to coriolis effect

Question 13

What air is the core of the jet stream

Answer 13

Warm air

Question 14

Where do jet streams form

Answer 14

The warmer air below the tropopause

Question 15

Approximate figures to remember for different JS

Answer 15

Artic front, 20000ft, lat 60
Polar front, 30000ft, lat 50
Sub tropical, 40000ft, lat 40
Equitorial easterly, 45000ft, lat 10

Question 16

How could low level jets occur

Answer 16

Due to nocturnal radiation and temp inversion in mountainous areas which shield the jet from surface friction
They could be as low as 5000ft

Question 17

What do low level js produce

Answer 17

Extreme wind Shear and turbulence and are associated with barriers and surface inversions

Question 18

What is the relationship between temp and pressure

Answer 18

If have a lower temperature = more dense = quicker pressure drop = less pressure

Question 19

What does a pressure difference mean

Answer 19

There is wind
Strong wind = steep pressure gradient = steep temp gradients

Question 20

What is the difference in the sub tropical js between winter and summer

Answer 20

It is STRONGER in winter than in summer

Question 21

What is a quality of the polar front js

Answer 21

It moves with polar front depressions
It isn’t consistent or permanent in position / said to follow the sun

Question 22

If a js is going from east to west where is the cold air and warm air

Answer 22

Cold air is above and warm air is below
So
If heading south then temp increases and if heading north temp decreases