Question

Greenhouse effect refers to
(a) Cooling of Earth
(b) Trapping of UV rays
(c) Production of cereals
(d) Warming of Earth

Answer 1

Hint: When the energy of the Sun reaches the Earth’s atmosphere in the form of light, some of this light energy is reflected back to space but the rest of the parts of this energy is absorbed by the greenhouse gases and is re-radiated.

Complete answer: The greenhouse effect is a natural process that keeps the Earth’s surface warmer by trapping the energy of the Sun that comes to the Earth in the form of light. It is the greenhouse effect that makes the Earth a suitable place for living organisms. It is a natural process and some gases take part in this that are known as greenhouse gases. Water vapor, nitrous oxide, methane, carbon dioxide, ozone, and CFCs come under the category of greenhouse gasses. A diagrammatic representation of the greenhouse effect is given below –
It occurs in the following steps –
1. The Solar radiation reaches the Earth's atmosphere and some part of this radiation is reflected back while the rest part of this energy is absorbed by the lands and the oceans and other objects on the Earth which heats up the Earth.
2. Heat is radiated from the Earth towards space but some of this heat is trapped by greenhouse gases that are present in the Earth’s atmosphere and this trapped heat keeps the Earth warm enough.
So, the correct answer is ‘Warming of Earth’.

Note:
1. In the absence of greenhouse gases, the surface temperature of the Earth would be around -18°C while the present average temperature is 15°C.
2. Clouds also have been found to absorb and emit infrared radiation and thus they have an effect on greenhouse gas radiative properties.