Q: How solar energy keep the earth warm during the night ?
Sol: A greenhouse is a building with glass roof and sides, it is used mainly in cold countries to grow plants that need warm conditions. Here, glass plays an important role. It allows infrared radiation of shorter wavelength to pass through it, but it reflects infrared radiation of longer wavelengths. CO2 also shows this kind of behavior. Now solar radiation passing through the glass heats up objects inside the greenhouse. These war, objects radiate heat in the longer infrared radiation. These radiations are reflected by the glass roof and walls, thus trapping heat inside the greenhouse. This trapped heat inside greenhouse keeps the greenhouse warm even at night. This is called green house effect. Similarly cars parked in the sun during summer becomes heated up due to greenhouse effect.
During the day earth’s surface is heated up by solar radiation. Once the surface becomes hot it starts radiating infrared radiation., the CO2 present in the atmosphere reflects back this infrared radiation to the surface of the earth. This trapped solar energy keep the earth warm during the nigh. This is due to the greenhouse effect.