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Question
A student claims that because of atmospheric refraction, the sun can be seen after it has set, and the day is, therefore, longer than if the earth had no atmosphere.
Do you think that the students conclusion is correct?
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Solution
Yes, the student's conclusion about the longer duration of the day because of atmospheric refraction is correct. Atmospheric refraction causes the sun to appear two minutes before the actual sunrise and two minutes after sunset. Therefore, the time from sunrise to sunset is increased by about four minutes. Thus, the day gets longer by about four minutes than if the earth had no atmosphere.
RELATED QUESTIONS
What is atmospheric refraction? Use this phenomenon to explain the following natural events:
Twinkling of stars
Draw diagrams to illustrate your answers.
What is atmospheric refraction? Use this phenomenon to explain the following natural events:
Advanced sun-rise and delayed sun-set.
Draw diagrams to illustrate your answers.
The correct sequencing of angle of incidence, angle of emergence, angle of refraction and lateral displacement shown in the following diagram by digits 1, 2, 3 and 4 is:
(a) 2, 4, 1, 3
(b) 2, 1, 4, 3
(c) 1, 2, 4, 3
(d) 2, 1, 3, 4
Name the phenomenon which causes the twinkling of stars.
Why do stars seem higher than they actually are? Illustrate your answer with the help of a diagram.
What is atmospheric refraction?
The stars twinkle but the planets do not twinkle at night because:
(a) the stars are small but the planets are large
(b) the stars are very large but planets are small
(c) the stars are much nearer but planets are far off
(d) the stars are far off but planets are nearer to earth
Due to atmospheric refraction of sunlight, the time from sunrise to sunset is lengthened by about:
(a) 6 minutes
(b) 2 minutes
(c) 4 minutes
(d) 5 minutes
The day is longer on the earth by about 4 minutes because:
(a) the earth is round in shape
(b) the earth rotates on its axis
(c) the earth revolves around the sun
(d) the earth has atmosphere
State one effect produced by the scattering of light by the atmosphere.
Which of the following is not caused by the atmospheric refraction of light?
(a) twinkling of stars at night
(b) sun appearing higher in the sky than it actually is
(c) sun becoming visible two minutes before actual sunrise
(d) sun appearing red at sunset
A star sometimes appears brighter and some other times fainter. What is this effect called? State the reason for this effect.
The stars appear higher from horizon than they actually are. Explain why it is so.
Explain why the planets do not twinkle but the stars twinkle.
Refraction of light by the earth’s atmosphere due to variation in air density is called ____________.
Assertion: Sky appears blue in the day time.
Reason: White light is composed of seven colours.
How does refraction take place in the atmosphere? Why do stars twinkle but not the planets?
