What is Greenhouse effect?

‘Greenhouse Effect’ is defined  as ‘The progressive warming up of earth’s surface due to blanketing effect of manmade CO₂ in the atmosphere.’

A greenhouse is that body which allows the short wavelength incoming solar radiation to come in, but does not allow the long wave outgoing infra-red radiation to escape. The earth’s atmosphere bottles up the energy of the sun and it acts like a green house, where CO₂  acts like a glass windows.