ThunderstormAviation Meteorology — DGCA CPL practice questions
Question 1 of 44
The condition necessary for the formation of a thunderstorm are
All 44 questions — Thunderstorm
Aviation Meteorology · DGCA CPL. The correct option is marked on each.
Q1. The condition necessary for the formation of a thunderstorm are
- A.Steep lapse rate, strong winds
- B.Shallow lapse rate, adequate supply of moisture
- C.Steep lapse rate, adequate supply of moisture and trigger action✓
Why: TS needs instability, moisture and a trigger/lifting mechanism.
Q2. Hail is most likely to fall from a cloud
- A.Having layers of ice crystals
- B.Composed of ice crystals
- C.Having strong vertical development✓
Why: Hail forms in deep clouds with strong vertical currents.
Q3. Norwesters are
- A.The western disturbances which affect NW India
- B.Severe thunderstorms which occur over NE India during hot weather period✓
- C.Severe thunderstorms which occur over Peninsula during hot weather period
Why: Norwesters are severe pre-monsoon TS over east/northeast India.
Q4. Duststorm occurs over NW India during
- A.Post-monsoon
- B.Winter
- C.Pre-Monsoon✓
Why: Dust storms over NW India occur in the hot pre-monsoon season.
Q5. A 'mature' thunderstorm has strong
- A.updraft only
- B.downdraft only
- C.updrafts and downdraughts✓
Why: Mature stage has coexisting up- and down-draughts.
Q6. Aircraft icing is most favoured in the cloud at temperatures ranging between
- A.−20°C and −40°C
- B.0°C and −20°C✓
- C.below −40°C
Why: Supercooled water most abundant between 0 and −20°C, giving worst icing.
Q7. A short duration, showery precipitation is associated with
- A.ST
- B.AS
- C.CB✓
Why: Showers come from convective cumulonimbus.
Q8. The most hazardous cloud for aviation is
- A.CB✓
- B.CU
- C.NS
Why: Cumulonimbus contains turbulence, hail, icing and lightning.
Q9. The life of a Cb cell is usually
- A.7 to 8 hrs
- B.3 to 4 hrs
- C.2–3 hr✓
Why: A single CB cell lasts roughly 2–3 hours.
Q10. Generally the mature activity of a heat type, TS is for
- A.2 hrs
- B.30 to 45 min✓
- C.3 to 4 hr
Why: Peak activity of a heat TS lasts about 30–45 minutes.
Q11. Norwesters occur during
- A.Jan–Feb
- B.Mar–May✓
- C.Jun–Sep
Why: Norwesters occur in the hot pre-monsoon months March–May.
Q12. Norwesters affect
- A.N India
- B.Bengal, Bihar, Orissa and Assam✓
- C.Central India
Why: Norwesters affect the eastern states of Bengal, Bihar, Orissa and Assam.
Q13. The trigger action may take place due to
- A.Clear night sky, no wind
- B.Orographic lifting✓
- C.high pressure
Why: Orographic lifting provides the trigger action for convection.
Q14. Norwesters normally occur during
- A.Mornings
- B.Afternoons✓
- C.Nights
Why: Convective Norwesters develop with afternoon heating.
Q15. Norwesters originates over
- A.Chota-Nagpur hills✓
- B.Deccan Plato
- C.Khasi hills
Why: Norwesters originate over the Chota Nagpur plateau region.
Q16. Andhi (blinding storms) occur generally over
- A.S India
- B.N India✓
- C.NE India
Why: Andhi dust storms occur over north/northwest India.
Q17. Wind speed in Light DS is
- A.25 kt
- B.30 kt
- C.up to 21 kt✓
Why: A light dust storm has winds up to about 21 kt.
Q18. The diametre of Microburst is
- A.less than 4 km✓
- B.less than 2 km
- C.less than 6 km
Why: A microburst outflow is less than 4 km across.
Q19. The diametre of and Macroburst
- A.<4 km
- B.4 km or more✓
- C.>8 km
Why: A macroburst outflow is 4 km or more across.
Q20. For detecting precipitation a Radar wavelength in the range ……… is suitable
- A.30 to 200 mm✓
- B.400–500 mm
- C.600–700 mm
Why: Weather/precipitation radars use centimetric wavelengths, about 30–200 mm.
Q21. For airborne radars wavelength generally used
- A.20 mm
- B.40 mm✓
- C.60 mm
Why: Airborne weather radar uses a wavelength of about 3–4 cm.
Q22. The wavelength of TS detection X band radar is
- A.10 mm
- B.20 mm
- C.30 mm✓
Why: X-band wavelength is about 30 mm.
Q23. The wavelength of storm detection S band radar is
- A.50 mm
- B.100 mm✓
- C.200 mm
Why: S-band wavelength is about 100 mm.
Q24. Over plains TS mostly occur during the
- A.afternoon✓
- B.night
- C.early morning
Why: Over plains, surface heating causes afternoon thunderstorms.
Q25. Over valley and foot hills TS generally occur during
- A.afternoon
- B.night & early morning✓
- C.early morning
Why: Katabatic/convergence effects give night & early-morning TS in valleys.
Q26. Over the sea TS are more frequent
- A.afternoon
- B.night✓
- C.early morning
Why: Over sea the surface is warmest relative to air at night, favouring nocturnal TS.
Q27. The life of Mesoscale Convective Complex is
- A.2-3 hr
- B.3-4 hr
- C.6 to 24 hr✓
Why: An MCC persists for roughly 6 to 24 hours.
Q28. Loud peals of thunder, frequent flashes of lightning, moderate or heavy showers accompanied by light wind hail speed 15-40 kt are characteristic of a TS of intensity
- A.Having layers
- B.Moderate TS✓
- C.Severe TS
Why: Winds 15–40 kt with moderate/heavy showers define a moderate thunderstorm.
Q29. For a severe TS one of the requirements is strong Wind Shear
- A.Horizontal
- B.Vertical✓
- C.Slant
Why: Strong vertical wind shear organises and sustains severe TS.
Q30. When flying through an active TS, lighting strikes are most likely
- A.Above 5000 ft and under the anvil
- B.In the clear air below the cloud in rain
- C.In the temperature band between +10° and −10°C✓
Why: Lightning strikes to aircraft are most common near the 0°C level, in the +10 to −10°C band.
Q31. Hazards of TS to aircraft of a TS Cell include turbulence, lightning, and
- A.Microburst, wind shear and anvil
- B.Icing, microburst and WS✓
- C.—
Why: Additional TS hazards are icing, microburst and wind shear.
Q32. Hail grows as it freezes as it
- A.freezes as it falls
- B.up and down forces in CU cloud
- C.collision with ice crystals
- D.collision with supercooled water drops✓
Why: Hailstones grow by accreting supercooled water drops that freeze on them.
Q33. Dust Storm usually occurs over NW India during
- A.Post-monsoon
- B.Winter
- C.Pre-Monsoon✓
Why: Dust storms over NW India occur in the hot pre-monsoon season.
Q34. A 'mature' thunderstorm has
- A.updraft only
- B.downdraft only
- C.updrafts and downdrafts✓
Why: Mature stage has both up- and down-draughts.
Q35. Aircraft icing is most favoured in the cloud which have temperatures ranging between
- A.20° C and 40° C
- B.0° C and - 20° C✓
- C.below 40 ° C
Why: Worst icing occurs between 0°C and −20°C where supercooled water is abundant.
Q36. Generally the severest activity of a, heat type, TS is for
- A.2 hrs
- B.30 to 45 min✓
- C.3 to 4 hr
Why: Severest activity of a heat TS lasts about 30–45 minutes.
Q37. The trigger action may take place due ro
- A.Clear night sky no wind
- B.Orographic lifting✓
- C.high pressure
Why: Orographic lifting provides trigger action for convection.
Q38. The diameter of Microburst is
- A.less than 4 km✓
- B.less than 2 km
- C.less than 6 km
Why: A microburst is less than 4 km in diameter.
Q39. The diameter of and Macroburst
- A.< 4 km
- B.4 km or more✓
- C.> 8 km
Why: A macroburst is 4 km or more in diameter.
Q40. The life of Mesoscale Convective Complex TS is
- A.6 to 24 hr✓
- B.3-4 hr
- C.2-3 hr
Why: A Mesoscale Convective Complex persists for 6 to 24 hours.
Q41. Loud peals of thunder, frequent flashes of lightning, moderate or heavy showers accompanied by light hail with maximum wind speed 15-40 kt is classified as
- A.Light TS
- B.Moderate TS✓
- C.Severe TS
Why: Winds 15–40 kt define a moderate TS; '1540 kt' OCR garble repaired to 15–40 kt.
Q42. When flying through on active TS, lightning strikes are mostly likely
- A.Above 5000 ft and under the anvil
- B.In the clear air below the cloud in rain
- C.In the temperature band between +10 C and -10 C✓
- D.At or above 10000 ft
Why: Lightning strikes are most likely in the +10 to −10°C band near the freezing level.
Q43. Hazards of the mature stage of TS Cell include lighting, turbulence and
- A.Microburst, windshear and anvil
- B.Icing, microburst and WS✓
- C.Icing, drizzle and microburst
- D.WS, hail and fog
Why: Further mature-stage hazards are icing, microburst and wind shear.
Q44. Hail grows by
- A.freezing as it leaves the cloud
- B.up and down forces in CU cloud
- C.collision with ice crystals
- D.collision with supercooled water drops✓
Why: Hail grows by collecting and freezing supercooled water drops.