Mountain WavesAviation Meteorology — DGCA CPL practice questions
Question 1 of 12
For mountain waves to form there should be flow of air across the ridge, generally within ……… of the perpendicular to the ridge.
All 12 questions — Mountain Waves
Aviation Meteorology · DGCA CPL. The correct option is marked on each.
Q1. For mountain waves to form there should be flow of air across the ridge, generally within ……… of the perpendicular to the ridge.
- A.30°✓
- B.45°
- C.60°
Why: Airflow must be within about 30° of perpendicular to the ridge for wave formation.
Q2. For mountain waves to form, the wind speed for small mountains should be at least
- A.15 m/s
- B.10 m/s
- C.7 m/s✓
Why: Minimum wind for small hills is about 7 m/s at ridge level.
Q3. For mountain waves to form, the wind speed for large mountains should be at least
- A.15 m/s✓
- B.10 m/s
- C.7 m/s
Why: Large mountain ranges require at least about 15 m/s at ridge level.
Q4. For mountain waves to form there should be ….. air below the ridge and less stable air above.
- A.Stable✓
- B.Unstable
- C.Indifferent
Why: A stable layer at/below ridge with less stable air above supports lee waves.
Q5. The worst kind of turbulence is encountered in the vicinity of rotor clouds.
- A.Rotor Clouds✓
- B.Lenticular Clouds
- C.Cap Clouds
Why: The most severe turbulence occurs near rotor clouds beneath wave crests.
Q6. In Mountain waves the Rotor clouds form in
- A.Troughs✓
- B.Ridges
- C.Valley
Why: Rotors form in the troughs of the lee waves, beneath the crests.
Q7. Clear air turbulence is often encountered
- A.At the boundary of a jet stream✓
- B.In the wake of a passing airplane
- C.In the wake of a larger airplane at take off and landing
- D.All of the above
Why: CAT is associated with jet-stream boundaries; the wake options are wake turbulence, not CAT.
Q8. Most CAT occurs on the ……… of a jet stream and in the vicinity of upper level frontal zones where temperature contrasts are strong.
- A.Fringes✓
- B.Within the core
- C.Axis
Why: CAT is strongest on the fringes of the jet where shear is greatest.
Q9. CAT is the bumpiness experienced by aircraft at high altitudes. Over North India its maximum frequency is during
- A.Oct–May✓
- B.Jul–Aug
- C.Jun–Sep
Why: Over North India CAT peaks during the winter/westerly-jet season, Oct–May.
Q10. When approaching an area where mountain waves have been reported, a pilot should expect
- A.Possible presence of roll clouds and lenticular clouds
- B.Intense up draughts and down draughts on the lee side of the mountains
- C.Moderate to severe turbulence as far as 20 to 30 nm from range on leeward side
- D.All of the above✓
Why: All listed effects accompany reported mountain-wave activity.
Q11. For mountain waves to form the atmosphere should be ……. up to the ridge, where air stream strikes the ridge.
- A.Unstable
- B.Stable✓
- C.Indifferent
Why: Stable stratification up to ridge level is required for wave formation.
Q12. CAT is the bumpiness experienced by aircraft at high altitudes ……. in either cloudfree conditions or in stratiform clouds
- A.above 18,000 feet✓
- B.below 18,000 feet
- C.below 28,000 feet
Why: CAT is high-altitude turbulence, generally above 18,000 ft.