Mountain Waves

Question 1

Define mountain waves

Answer 1

Waves or ripples which form in the atmosphere caused by air encountering an obstruction or barrier at the surface of the earth

Question 2

List the 4 factors that affect the evolution of mountain waves

Answer 2

Obstruction
Stable layer
Strong wind
Weak directional shear

Question 3

The wavelength and strength of the vertical currents are affected by:

Answer 3

The width of the obstruction

Question 4

The amplitude and strength of the vertical currents are affected by:

Answer 4

the lee side fall (sudden drop)

Question 5

The waves immediately following the obstruction are the __________

Answer 5

strongest and get progressively weaker

Question 6

A stable layer must be present just ______ the barrier

Answer 6

above

Question 7

The minimum speed at which wind will create a mountain wave i:

Answer 7

25kts

Question 8

An angle of incidence of ____ degrees each side of the barrier is the maximum allowable deviance

Answer 8

30

Question 9

List the 3 cloud types associated with mountain waves:

Answer 9

Cap
Rotor
Lenticular

Question 10

What type of lift creates cap clouds and what dissipates them on the other side?

Answer 10

Orographic lift

Adiabatic heating

Question 11

Rotor clouds form past the obstruction as a result of __________. they appear as ___________

Answer 11

Turbulent mixing

long line of stratocumulus

Question 12

Wave crests may be marked with:

Answer 12

Lenticular clouds

Question 13

lenticular clouds at mid levels are called

Answer 13

ACSL Altocumulus standing lenticular

Question 14

What are the most dangerous element of mountain waves?

Answer 14

Rotor Clouds

Question 15

List the 5 hazards to aviation associated with mountain waves

Answer 15

Wind shear
Obscured terrain
Turbulence
Up/downdrafts
Changes in pressure

Question 16

Downdrafts are most severe:

Answer 16

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

Question 17

Increased wind speed in the wave crests cause a:

Answer 17

lowering of the pressure (bernouilli)

Question 18

the most turbulent area of in a mountain wave system is:

Answer 18

the rotor

Question 19

Strong vertical wind shears are often concentrated ____________ the jet stream

Answer 19

Just above and below

Question 20

Mountain waves are more pronounced on the __________ side of the jet stream

Answer 20

warm