Advertisements
Advertisements
Question
The colour of clear sky from the earth appears blue but from the space it appears black. Why?
Solution
The molecules of air and other fine particles in the atmosphere have size smaller than the wavelength of visible light. These are more effective in scattering light of shorter wavelengths at the blue end than light of longer wavelengths at the red end. The red light has a wavelength about 1.8 times greater than blue light. Thus, when sunlight passes through the atmosphere, the fine particles in air scatter the blue colour (shorter wavelengths) more strongly than red. The scattered blue light enters our eyes. If the earth had no atmosphere, there would not have been any scattering. Then, the sky would have looked dark.
APPEARS IN
RELATED QUESTIONS
What is meant by scattering of light? Use this phenomenon to explain why the clear sky appears blue or the Sun appears reddish at sunrise.
Name a natural phenomenon which is caused by the dispersion of sunlight in the sky.
Which phenomenon makes us see the sun:
a few minutes after actual sunset?
Sunset is red because at that time the light coming from the sun has to travel:
(a) lesser thickness of earth's atmosphere
(b) greater thickness of earth's atmosphere
(c) varying thickness of earth's atmosphere
(d) along the horizon
In white light of sun, maximum scattering by the air molecular present in the earth’s atmosphere is for ______.
Explain in brief the reason for the following:
Twinkling of stars
Draw a labeled diagram to show
(i) the reddish appearance of the sun at the sunrise or the sunset and
(ii) white appearance of the sun at noon when it is overhead.
Answer the following question:
Why is the Tyndall effect shown by colloidal particles? State four instances of observing the Tyndall effect.
Draw a labelled diagram to show (i) reddish appearance of the sun at the sunrise or the sunset and (ii) white appearance of the sun at noon when it is overhead.
The clear sky appears blue because
