Dear student,
Greenhouse effect - The reabsorption of thermal radiation from the surface of the Earth by greenhouse gases is called greenhouse effect. The greenhouse gases(water vapour, CO2, N2O and CH4 ) act as a blanket around the earth, raising Earth's temperature.
Application -
The greenhouse gases shield the atmosphere from the unwanted solar radiation. Ozone, present in the stratosphere absorbs harmful ultraviolet rays of the sun. Without their protective covering, all the harmful rays would have been radiated back to the Earth's surface and affect adversely.
Regards.