Question

Our atmosphere acts as a greenhouse. Explain.

Answer 1

Hint: The greenhouse effect is defined as the phenomenon of an increase in temperature of the earth’s surface caused by the presence of particular gases naturally in the atmosphere with selective absorption properties in the atmosphere. The greenhouse effect is the prime reason for the existence of life on earth.

Complete step by step answer:
The atmosphere comprises gases like \[C{O_2}\]​ water vapour, ${O_3}$​, \[C{H_4}\] oxides of nitrogen, and $CFC's$. These gases are radiative gases and are called greenhouse gases.
These gases permit the sunrays to get trapped inside the earth’s surface. The Sunlight which reaches the earth consists of three types of radiation \[ - UV\], visible radiation, and \[IR\]radiation.
As the sunlight enters the atmosphere, most of the UV radiation gets absorbed by the ozone, \[30\;\% \] of \[IR\] radiation reaches the ground which results in heating up of the surface. As the surface of earth gets hotter, it begins emitting radiation having less energy than the incoming radiation with a longer wavelength.
 Some of the emitted radiation escapes the Earth’s surface and some get absorbed by the gases like \[C{O_2}\]​, thus remaining in the Earth. The Trapped radiation warms the Earth’s surface and lower layers of the atmosphere.
Other than the naturally occurring gases there are many gases introduced through human activities in the atmosphere which helps in the greenhouse effect. Thus, Our atmosphere acts like a greenhouse.

Note:
If there was no greenhouse effect in nature then it is estimated that global the temperature of earth would be $ - {18^0}C$. This implies that life would not have sustained on earth. In the last century, it has been observed by the scientist that there is a great upsurge in the amount of greenhouse gases in the atmosphere due to various human activities causing a rise in the average global temperature. They have predicted that if the emissions of these gases keep increasing without any control then the earth’s global temperature will increase by ${2.5^0}C$ by $2050$.