If the earth did not have an atmosphere, it would become intoleraby cold. Why?

Explanation

In the absence of earth's atmosphere, the thermal radiation (i.e., infrared radiations) emitted by earth at night would not be reflected back and there would not be reflected back and there would be no green house effect on earth. As a result of it, the earth's mean temperature would dorp to `-18^(@)C`, which is very low. At this temperature , water on earth will freeze and most of low. At this temperature, water on earth will freeze and most of life on earth would not survive.