DGCA Meteorology: Optical Phenomena Questions
20 exam-style Optical Phenomena questions for the DGCA Meteorologypaper (CPL & ATPL). The first 12 are free below with answers and explanations — sign up free to practise all of them with progress tracking.
- Q1
Aurora Australis occur in the
- AS hemisphere
- BN hemisphere
- CEquator
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Correct answer: A. S hemisphere
The Aurora Australis occurs at high latitudes of the Southern Hemisphere, produced by charged solar particles entering the upper atmosphere near the magnetic pole.
- Q2
Aurora Australis called _____ Lights
- ANorthern
- BSouthern
- CTemperate
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Correct answer: B. Southern
Aurora Australis means the Southern Lights, the Southern Hemisphere counterpart of the Aurora Borealis.
- Q3
Aurora Borealis occur in the
- AS hemisphere
- BN hemisphere
- CEquator
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Correct answer: B. N hemisphere
The Aurora Borealis occurs at high latitudes of the Northern Hemisphere.
- Q4
Aurora Borealis are called ______ Lights
- ANorthern
- BSouthern
- CTemperate
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Correct answer: A. Northern
Aurora Borealis are the Northern Lights, seen at high northern latitudes.
- Q5
Corona occur in ______ clouds
- AAS
- BNS
- CCS
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Correct answer: A. AS
A corona forms by diffraction of light in thin cloud of small water droplets, and of the clouds in question a thin altostratus veil produces it; cirrostratus is ice crystal cloud giving a halo, and nimbostratus is far too thick to show optical rings.
- Q6
Bishop's ring is due to the diffraction of light by fine particles of
- AWater
- Bdust
- Cice
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Correct answer: B. dust
The Bishop's ring is a dull reddish-brown ring around the sun caused by diffraction of light by fine particles of volcanic dust suspended in the high atmosphere.
- Q7
The radius of the Bishop's ring is about
- A32°
- B22°
- C42°
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Correct answer: B. 22°
The Bishop's ring appears as a broad diffraction ring around the sun with an angular radius of about 22 degrees.
- Q8
Superior Mirage occurs marked
- ALapse
- BIsothermal
- CInversion
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Correct answer: C. Inversion
A superior mirage, in which the image appears above the true position of the object, occurs with a marked temperature inversion, the light rays being bent downward over the dense cold air near the surface.
- Q9
Inferior Mirage occurs when there is
- ALapse
- BIsothermal
- CInversion
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Correct answer: A. Lapse
An inferior mirage, such as the sheet of apparent water on a hot road, occurs when a steep temperature lapse above a strongly heated surface bends light rays upward, displacing the image below the object.
- Q10
Corona are formed due to the ______ of light
- ARefraction
- BDiffraction
- CScattering
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Correct answer: B. Diffraction
A corona is formed by diffraction of light as it passes around small, uniform water droplets, producing coloured rings close about the sun or moon.
- Q11
Corona are formed due to light, passing through
- AMist only
- BFog only
- Csmall water or ice particles only
- DAny one of all these
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Correct answer: D. Any one of all these
A corona is produced whenever light is diffracted by sufficiently small, uniform particles, whether in mist, in fog, or in thin cloud of tiny water or ice particles, so any of these media can give rise to it.
- Q12
Halo is produced by
- ARefraction
- BDiffraction
- CScattering
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Correct answer: A. Refraction
A halo is produced by refraction of light through hexagonal ice crystals; diffraction by water droplets produces the corona instead.
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