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Q56
(IAS/2002)
Geography › World Physical Geography › Atmospheric moisture
Answer Verified
Sun’s halo is produced by the refraction of light in
Result
Your answer:
—
·
Correct:
C
Explanation
Halos around the Sun (for example the common 22° halo) are optical phenomena produced when sunlight is refracted and reflected by ice crystals suspended in high, thin clouds. Text sources state halos are caused by refraction and reflection by ice crystals in cirrus clouds [1], and that cirrus clouds are composed of ice crystals at high altitudes [2]. The classic 22° halo forms when sunlight passes through hexagonal ice crystals and is bent like a prism, producing a circular ring. Therefore ice crystals in cirrus/cirrostratus clouds are responsible; low-level stratus clouds (liquid water droplets) or airborne dust do not produce the same refractive ring structure.
Sources
- [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 24: Hydrological Cycle (Water Cycle) > Explanation: > p. 335
- [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 24: Hydrological Cycle (Water Cycle) > Cirrus Clouds > p. 333
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