What is a green house ? Why is air warmer in green that outside ?

Explanation

A building chiefly made of glass for groving or shettering the delicate plants is called green house.
The glass walls of green house allow sun rays to pass into the interior right upto earth's surface. Howerver, reflected back infrared rays not allowed to escaps by the glass walls as wells as `CO_(2)` gas and water vapours present in the air, inside the glass walks. This makes green house air warmer than outside air.