Question

what is greenhouse effect

Answer 1

the effect occures because of some gases like carbon monoxide, dioxide etc.

Answer 2

The sun rays directly do not enter into earth. They r filtered by ozone layer from harmful chemicals or rays. And the amount of rays again which enters into earth are reflected by clouds, water vapour and the land and oceans. The smoke particles which are released by vehicles or factories make a screen like covering in the atmosphere preventing the sunlight from going back after reflection. This increases the amount of heat on earth. This is called green house effect
Hope it helps you