WindsAviation Meteorology — DGCA CPL practice questions
Question 1 of 43
In the Southern Hemisphere, if an observer faces the wind, the low pressure is to their:
All 43 questions — Winds
Aviation Meteorology · DGCA CPL. The correct option is marked on each.
Q1. In the Southern Hemisphere, if an observer faces the wind, the low pressure is to their:
- A.Right
- B.Left✓
Why: SH: back to wind → low on the right; facing the wind → low on the left.
Q2. In the Northern Hemisphere, due to the earth's rotation, winds are deflected to the:
- A.Left
- B.Right✓
Why: Coriolis deflects moving air to the right in the NH.
Q3. Local (thermal) winds obey Buys Ballot's law:
- A.False✓
- B.True
Why: Buys Ballot applies to large-scale gradient wind, not local winds.
Q4. In the Northern Hemisphere the Coriolis force acts perpendicular to the wind, to its:
- A.Left
- B.Right✓
Why: Coriolis acts 90° to the right of motion in the NH.
Q5. The geostrophic wind results from a balance between:
- A.Coriolis and friction
- B.Pressure gradient and cyclostrophic force
- C.Pressure gradient and Coriolis force✓
Why: Geostrophic balance = pressure-gradient force vs Coriolis force.
Q6. The Coriolis force is strongest at the:
- A.Mid-latitudes
- B.Poles✓
- C.Equator
Why: Coriolis is maximum at the poles, zero at the Equator.
Q7. The geostrophic approximation breaks down at the:
- A.Mid-latitudes
- B.Poles
- C.Equator✓
Why: Coriolis → 0 at the Equator, so geostrophic balance fails.
Q8. Föhn winds on the leeward side of a mountain are:
- A.Dry and warm✓
- B.Cold and humid
Why: Descending leeward air is warmed adiabatically and dried.
Q9. The wind sliding down a hillside at night is called a ____ wind:
- A.Föhn
- B.Anabatic
- C.Katabatic✓
Why: Katabatic = nocturnal downslope drainage wind.
Q10. With the onset of a sea breeze there is a ____ in temperature and a ____ in relative humidity:
- A.Fall / Rise✓
- B.Rise / Fall
- C.Fall / Fall
Why: Cool, moist sea air lowers temperature and raises RH.
Q11. A sea breeze sets in by ____ and dies off at ____:
- A.Night / Day
- B.Day / Night✓
- C.Both day and night
Why: Sea breeze blows during the day, ceasing at night.
Q12. In the NH, an aircraft flying from high to low pressure experiences:
- A.Starboard drift✓
- B.Port drift
Why: NH high→low: drift to starboard.
Q13. In the NH, if you experience port drift, the altimeter will read:
- A.Under✓
- B.Over
Why: Port drift ⇒ flying low→high pressure ⇒ altimeter under-reads.
Q14. Lines of constant wind speed on a chart are called:
- A.Isobars
- B.Isotachs✓
- C.Isogons
Why: Isotachs join points of equal wind speed.
Q15. A squall is distinguished from a gust by its:
- A.Shorter duration
- B.Longer duration✓
- C.Lower wind speed
Why: A squall is a sustained increase; a gust is momentary.
Q16. The thermal wind is:
- A.A wind caused by thermals
- B.A warm leeward downslope wind
- C.The vector to add to the lower geostrophic wind to obtain the upper geostrophic wind✓
Why: Thermal wind = vector difference between upper and lower geostrophic winds.
Q17. Where isobars are closely packed, the surface winds are likely to be:
- A.Light and parallel to the isobars
- B.Strong and parallel to the isobars✓
- C.Strong and blowing across the isobars
Why: Tight gradient → strong winds, near-parallel to isobars aloft.
Q18. Anabatic wind occurs:
- A.At night
- B.At any time
- C.During the day✓
Why: Anabatic = daytime upslope wind.
Q19. Anabatic wind is stronger than katabatic wind:
- A.True
- B.False✓
Why: Katabatic winds are generally the stronger of the two.
Q20. Katabatic wind is a downslope cold wind caused by nocturnal cooling:
- A.True✓
- B.False
Why: Correct — radiational cooling drains cold dense air downslope.
Q21. Katabatic wind is due to air sinking down the hill slope:
- A.True✓
- B.False
Why: Correct.
Q22. Anabatic wind is due to a downward movement of air along a valley:
- A.True
- B.False✓
Why: False — anabatic air moves UP-slope.
Q23. A sea breeze is stronger than a land breeze:
- A.True✓
- B.False
Why: The daytime land-sea temperature contrast is greater.
Q24. The wind blows clockwise around a low in the Northern Hemisphere:
- A.True
- B.False✓
Why: NH lows are anticlockwise.
Q25. The wind blows clockwise around a low in the Southern Hemisphere:
- A.True✓
- B.False
Why: SH lows are clockwise.
Q26. The wind blows anticlockwise around a low in the Northern Hemisphere:
- A.True✓
- B.False
Why: Correct for NH lows.
Q27. The wind blows anticlockwise around a low in the Southern Hemisphere:
- A.True
- B.False✓
Why: False — SH lows are clockwise.
Q28. The wind under the combined influence of pressure-gradient, Coriolis and centrifugal (cyclostrophic) forces is the:
- A.Gradient wind✓
- B.Geostrophic wind
- C.Cyclostrophic wind
Why: The gradient wind accounts for curved flow.
Q29. From day to night for a fixed isobaric pattern (NH), the surface wind:
- A.Backs and weakens✓
- B.Veers and strengthens
Why: At night reduced mixing → surface wind backs and weakens.
Q30. Winds spiralling inward anticlockwise in the NH are associated with a:
- A.Turbulence zone
- B.High-pressure area
- C.Low-pressure area✓
Why: Inward anticlockwise spiral = low pressure.
Q31. Lower-level wind 050/10 kt, upper-level wind 230/05 kt. The thermal wind is:
- A.050/05 kt
- B.230/15 kt✓
- C.050/15 kt
Why: Directions are opposite; thermal wind = 230/ = 230/15 kt.
Q32. A change in wind direction from 310° to 020° is:
- A.Backing
- B.Veering✓
Why: Clockwise change = veering.
Q33. A change in wind direction from 270° to 250° is:
- A.Backing✓
- B.Veering
Why: Anticlockwise change = backing.
Q34. A change in wind speed from 10 kt to 30 kt and back to 15 kt is a:
- A.Gust✓
- B.Squall
- C.Gale
Why: A brief peak then drop = a gust.
Q35. A rise in wind speed from 10 kt to 30 kt sustained for 2–3 minutes is a:
- A.Squall✓
- B.Gust
Why: A sustained increase = a squall.
Q36. Significant wind shear can be associated with a thunderstorm or line squall:
- A.False
- B.True✓
Why: Correct — gust fronts/outflows cause strong shear.
Q37. The cyclostrophic wind gives a good approximation of the 2000 ft wind in an intense tropical storm:
- A.True✓
- B.False
Why: In intense, tightly-curved systems the centrifugal term dominates.
Q38. Rotor clouds indicate extremely turbulent flying conditions:
- A.False
- B.True✓
Why: Rotor zones are severely turbulent.
Q39. Friction makes the wind cross the isobars by about ____ over land and ____ over sea:
- A.20° / 10°✓
- B.20° / 30°
- C.40° / 30°
Why: Greater friction over land than sea.
Q40. If the south is warmer than the north at every level (NH), the ____ wind strengthens with height without changing direction:
- A.Easterly
- B.Westerly✓
- C.Southerly
- D.Northerly
Why: Warm south / cold north → thermal wind westerly → upper westerlies strengthen.
Q41. In an anticyclone, the gradient wind relative to the geostrophic wind is:
- A.An under-estimate
- B.Accurate
- C.An over-estimate✓
Why: Gradient wind is supergeostrophic in an anticyclone.
Q42. In the NH the thermal wind blows parallel to the ____ with the lower values (cold) on its left:
- A.Isobars
- B.Isotherms✓
- C.Isallobars
Why: Thermal wind is parallel to the thickness lines/isotherms, cold on the left.
Q43. Inertial flow is:
- A.Cyclonic in both hemispheres
- B.Anticyclonic in both hemispheres✓
- C.Anticyclonic only around an anticyclone
Why: Inertial oscillation is anticyclonic in both hemispheres.