Stability and Instability of AtmosphereAviation Meteorology — DGCA CPL practice questions
Question 1 of 16
DALR = 9.8°C, ELR = 6.8°C — atmosphere is
All 16 questions — Stability and Instability of Atmosphere
Aviation Meteorology · DGCA CPL. The correct option is marked on each.
Q1. DALR = 9.8°C, ELR = 6.8°C — atmosphere is
- A.stable✓
- B.unstable
Why: ELR less than DALR for dry air means stable.
Q2. SALR = 5.5°C, ELR = 4.5°C — atmosphere is
- A.unstable
- B.stable✓
- C.indifferent
Why: For saturated air ELR below SALR means stable.
Q3. DALR > ELR > SALR is
- A.conditionally unstable✓
- B.latently stable
- C.potentially stable
Why: ELR lies between SALR and DALR: conditional instability.
Q4. Dry air is unstable when
- A.ELR = DALR
- B.ELR > DALR✓
- C.ELR < DALR
Why: Dry air unstable when ELR exceeds DALR.
Q5. The saturated air is said to be unstable if
- A.SALR = ELR
- B.SALR < ELR✓
- C.SALR > ELR
Why: Saturated air unstable when ELR exceeds SALR.
Q6. Surface temp 30°C. Assuming DALR, temperature at 2 km is
- A.18°C
- B.10°C✓
- C.42°C
Why: 30 minus 10 per km times 2 km equals 10°C.
Q7. If ELR is less than SALR, atmosphere is said to be
- A.Absolutely unstable
- B.Conditionally unstable
- C.Absolutely stable✓
Why: ELR below SALR gives absolute stability.
Q8. DALR is approximately
- A.5°C/km
- B.15°C/km
- C.10°C/km✓
Why: Dry adiabatic lapse rate is about 9.8°C per km.
Q9. SALR at mean sea level is about
- A.10°C/km
- B.5°C/km✓
- C.5°F/km
Why: Saturated adiabatic lapse rate near MSL is about 5°C per km.
Q10. SALR approaches DALR
- A.at −15°C
- B.at −40°C✓
Why: At very low temperatures little moisture remains, SALR nears DALR near -40°C.
Q11. Dry air having a temp of 35°C on surface when forced to rise adiabatically by 1 km would attain a temp of
- A.29°C
- B.25°C✓
- C.45°C
Why: 35 minus about 10 per km cooling gives roughly 25°C.
Q12. Inversion in the atmosphere indicates
- A.Stability✓
- B.Instability
- C.Neutrality
Why: Temperature increase with height suppresses vertical motion, very stable.
Q13. Environmental LR can be more than DALR
- A.True✓
- B.False
Why: Superadiabatic ELR occurs over strongly heated surfaces.
Q14. The process which to a large extent determines the vertical distribution of temperature in atmosphere is
- A.Adiabatic✓
- B.Isothermal
- C.Isentropic
Why: Adiabatic processes govern vertical temperature structure.
Q15. Rise in temperature with height is
- A.Lapse
- B.Normal
- C.Inversion✓
Why: Temperature rising with height defines an inversion.
Q16. Inversion is common in
- A.Post Monsoon
- B.Monsoon
- C.Winters✓
Why: Nocturnal radiation inversions are most frequent in winter.