Question

Compare the following
(i) Wavelengths of the incident solar radiation absorbed by the earth’s surface and the radiation re-radiated by the earth.
(ii) Tanning effect produced on the skin by UV radiation incident directly on the skin and that coming through the glass window.

Answer 1

In comparison of the given statements, first of all read carefully the question and then make an analysis on that. Try to clear the facts given in the question by explanation of the number of statements given. Try to point out the facts regarding both the quantities to be compared.

Complete answer:
(1) In the solar system, any planet which absorbs energy is able to transmit that energy (not more than the absorbed energy) and it transmits energy in the form of radiation. Thus, the wavelength of the incident solar radiation which is absorbed by the surface of the earth is equal to the wavelength of the ray re-radiated by the earth.
(2) Tanning effect is of great importance for direct UV (Ultraviolet) radiation. When our skin is exposed to UV radiation then it increases the production of melanin. The melanin is produced in our body in order to prevent skin from further damage. Melanin is nothing but pigment that colors our hairs, eyes and skin and this increased amount of melanin pigment causes skin tone to become dark.
However, glass windows are very efficient in blocking most of the ultraviolet rays, however ultraviolet rays still manage to penetrate at some extent through the glass windows. The entrance of ultraviolet rays through glass windows can cause skin damage and other skin problems that could lead to skin irritation.

Note: Wavelength of the incident solar radiation is absorbed by the surface of the earth because of the fact that incoming radiation are electromagnetic wave named as visible and visible light has capacity to easily pass through the atmosphere but radiations which are re-directed by the earth are electromagnetic wave named as infrared not visible and infrared radiations are trapped in the greenhouse gases when they pass through the atmosphere.