Question

Write about the Greenhouse effect

Answer 1

Answer:

The greenhouse effect is the process by which radiation from a planet's atmosphere warms the planet's surface to a temperature above what it would be without this atmosphere. Radiatively active gases (i.e., greenhouse gases) in a planet's atmosphere radiate energy in all directions.

Answer 2

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:It is responsible for heating of earth’s surface and atmosphere. Without greenhouse effect, the average temperature of Earth would have been -180C rather than average of 150C. Of the solar radiation that reaches earth, Clouds and gases reflect about 1/4th and absorb some of it. But half of total incoming radiations reach the earth’s surface and heat it. Small portion of it, is reflected back. Earth’s surface re emits the heat in the form of infrared radiations. Part of these radiations do not escape into the space because atmospheric gases (CO2, CH4) absorb a major portion.

The molecules of these gases radiate heat energy and a major part of it comes back to earth’s surface. Thus reheating the earth. This cycle is repeated many times. Hence CO2 and CH4 are commonly called greenhouse gases.

The atmosphere around the earth acts as glass wall of a greenhouse. It absorbs solar radiations from the sun and radiates it to earth. Atmosphere prevents infrared radiations emitted by the earth to escape into the space. Gases responsible for this effect are carbon di-oxide (CO2), Methane (CH4), chloroflorocarbons (CFC), Nitrous oxide (N2O) and water vapours.

Because of burning of fossil fuels in industries, by automobiles, burning of agricultural wastes, levels of CO2 are increasing. Biogas plants, paddy fields, cattle sheds add methane to atmosphere. Chloroflorocarbons are emitted by fire extinguishers and air conditioners.