The sun is visible to us about two minutes before actual sunrise and about two minutes after the actual sunset. Give reason.
Advance sunrise and delayed sunset. Apparent shift in the position of sun at sunrise and sunset. The sun is visible before actual sunrise and after actual sunset, because of atmospheric refraction. With altitude, the density and hence refractive index of air-layer decreases. As shown in Fig., the light rays starting from the sun travel from rarer to denser layers. They bend more and more towards the normal. To an observer on the earth, light rays appears to come from position S’.The sun which is actually in position S below the horizon, appears in position S' above the horizon. Thus the sun appears to rise early by about two minutes and for the same reason, it appears to set late by about two minutes. This increases the length of the day by about four minutes.
Fig. Atmospheric refraction effect at sunrise
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Why do we observe the apparent random wavering or flickering of objects when seen through a turbulent stream of hot air rising above fire, a stove or radiator?
How does the colour of the scattered light depend on the size of the colloidal particles?
The sun near the horizon appears flattened at sunset and sunrise. Explain why?
Name two daily life phenomena based on scattering of light by atmospheric particles.
