Lesson 403 Mountain Waves

Question 1

Name the other terminology used to describe mountain waves.

SLOG

Answer 1

Standing waves
Lee waves
Orographic waves
Gravity waves

Question 2

List the four factors that affect the evolution of standing waves.
SOWS

Answer 2

Stable layer
Obstruction
Weak directional shear
Strong wind

Question 3

The horizontal extent of a mountain wave system varies from _____ to _____ km or more on the lee side of the barrier. Wavelengths can vary _____ to _____ km.

Answer 3

80 to 240 km

5 to 25 km

Question 4

A stable layer must be _______ _______ the crest of the barrier.

Answer 4

Just above

Question 5

The minimum speed at which a wind will create a mountain wave is _____ KT.

Answer 5

25 KT

Question 6

What is the maximum angle of incidence deviation from perpendicular allowable to form a mountain wave?

Answer 6

30 degrees

Question 7

What are the three cloud types associated with mountain waves? CLR

Answer 7

Cap cloud
Lenticular cloud
Rotor cloud

Question 8

What lifting process forms cap cloud and what process dissipates it on the lee side?

Answer 8

Orographic lift (adiabatic cooling)
Adiabatic heating

Question 9

Rotor clouds form past the obstruction as a result of _________ _________.

Answer 9

Turbulent mixing

Question 10

Lenticular clouds are formed and dissipated by:

Answer 10

Adiabatic cooling and heating

Question 11

List the five hazards to aviation associated with mountain waves:
TOWCU

Answer 11

Turbulence 
Obscured terrain 
Wind shear
Changes in pressure
Up and downdrafts

Question 12

Where are downdrafts most severe?

Answer 12

Near a mountain and at about the same height as the mountain top

Question 13

What is the most turbulent area in a mountain wave system?

Answer 13

The rotor