英语故事优秀读后感集合(7)

All life on Earth would be no life left the sunlight and the sun light is visible light, ultraviolet, infrared, three parts. Sunlight into the atmosphere （including UV）， 55% of light through the atmosphere to the earth and sea, of which 40% of visible light, which is the driving force for photosynthesis, green plants; 5% 100 — 400 nm wavelength ultraviolet light, and ultraviolet divided into long wave, medium wave, short wave ultraviolet light, UVA can sterilization.