What is Green House effect?
Green House Effect
The greenhouse effect received its name because the earth’s atmosphere acts much like the glass or plastic roof and walls of a greenhouse. Sunlight enters a greenhouse through the transparent glass of plastic and heat the plants but the heat emitted by the plants in the form of infrared radiation cannot pass through the glass or plastic roof and walls. As a result, the temperature inside increases. It is the phenomenon in which the earth’s atmosphere traps the heat form the sun and prevents it from escaping into outer space. Without this effect, the average surface temperature of the earth would be about 33°C lower than it is today.
In the atmosphere, there is a protective layer of O3, gas at a height between 15 — 60 km (the thickest layer of ozone exists at a height of 23 km from the surface of the earth and a blanket of CO2 gas exists in the lower part of the atmosphere (i.e., below 15 km). When sunlight consisting of ultraviolet rays, visible light and infrared, fall on the top of the atmosphere, the harmful ultraviolet rays are absorbed by the O3 layer and so these do not reach the earth’s surface.
However, the visible light and infrared rays pass though the CO2 layer and fall on the earth. The result is that the earth gets heated due to heating effect of the infrared radiations. As the earth becomes hot, it starts emitting heat (infrared rays) back to the atmosphere.
The emitted infrared rays are absorbed by the CO2, layer in the atmosphere. In this way, CO2, in the atmosphere does not allow the infrared radiation reflected by the earth’s surface to go out of the atmosphere. We can say that the layer of CO2, gas in the atmosphere traps all the infrared radiations (heat rays) coming from the earth’s surface. These trapped infrared rays heat the earth’s atmosphere. The heating up of the earth due to the trapping of infrared radiations (reflected from the earth’s surface) by CO2, layer in the atmosphere is called greenhouse effect. Thus, the temperature of the earth is raised. The rise in the temperature produced by the greenhouse effect in the earth’s atmosphere depends on the amount (proportion) of CO2, gas in the atmosphere.