CH9 - Turbulence and Windshear

Question 1

What is “friction layer”?

Answer 1

The layer of air disturbed.

Question 2

What is “friction level”?

Answer 2

Undisturbed UPPER flow
_________________________
Disturbed SURFACE flow

Question 3

What are the different types of turbulences?

Answer 3

Mechanical: By hills, trees, buildings… (loc: Towns, hills…)

Thermal: Formed by the warm air rising (loc: Areas with low albedo like rocky areas and fields)

Question 4

At which altitude diurnal variation is produced?

Answer 4

Between 2000-3000 ft.

Question 5

When is the time where the land reaches it coldest temperature? What happen with the friction level?

Answer 5

After sunrise. The friction level is at its lowest

Question 6

When is the time where the land reaches it warmest temperature? What happen with the friction level?

Answer 6

In the afternoon. The friction level is higher.

Question 7

What are microbusts?

Answer 7

Large amount of descending air.

Question 8

What conditions prevails mountain waves?

Answer 8

Stable air, wind of more than 15 kts and blows across the ridge.

Question 9

What sort of clouds might be formed when mountain waves are produced?

Answer 9

Lenticularis (up), roll clouds (down, near the surface) and cap cloud (sticked to the mountain).

Question 10

What is inversion?

Answer 10

The increase of temperature with height.

Question 11

How are turbulences classified regarding their intensity?

Answer 11

Light: 5-15 kts
Moderate: 15-25 kts
Severe: > 25kts