ICSE Class 9 Answered

The green house effect is an essential phenomenon to keep the earth's climate comfortable. From sun, we receive 1366 Wm^-2 energy at the top of our earth's atmosphere, out of which only 235 Wm^-2 energy reaches near the earth's surface. The earth and the ocean surface absorb 168 Wm^-2 energy and only 67 Wm^-2 energy remains in the lower atmosphere. With this much energy received on earth surface, its actual surface temperature would have been around -18^oC which is quite uncomfortable for human living. The green house gases present in the earth's  atmosphere contribute in trapping the heat energy within the atmosphere and they produce an average warming effect of about 33^oC to keep effective temperature of earth surface around 15^oC.