Question

The significance of greenhouse gases in earth's atmosphere is............

• A. They maintain a warm temperature on earth by absorbing short wave-length radiations.
• B. They do not allow earth's temperature to drop very low by spreading heat energy of long wavelength radiations
• C. They reflect Sun's heat back to atmosphere
• D. Both (1) and (2) .

Answer 1

The correct option is B They do not allow earth's temperature to drop very low by spreading heat energy of long wavelength radiations

If the earth had no atmosphere, its average surface temperature would be about -18 degrees. The average temperature of earth is 15 degrees. This is because the atmospheric cover around the earth acts like a glass walls of a green house. The gases in the atmosphere most responsible for keeping the earth's surface warm are carbon dioxide, methane , chlorofluorocarbons and water vapours. They are called green house gases. These gases absorb much of the incoming solar radiation from the sun and re radiates to the earth surface. However, they prevent the long wave infra red radiation emitted by the earth's surface to escape into the space.

Thus, the correct answer is option B.