UV rays
yes
Sunlight and oxygen.
A burn on the skin caused by excessive exposure to the sun or other sources of ultraviolet-A and -B radiation.
Sunburn is caused by UV-radiation from the sun which creates direct DNA damage.
I don't think so. Ulcers are generally caused by the bacteria H. pylori.
If you get at least 3 serious sunburns before the age of 20 there is an possibility that you will get skin cancer.
When the sky is high in the sky, the blue component of incoming sunlight is scattered much more than any other color component. Do your home work next time :D
Rainbow
It is caused by sunburn, overexposure to sunlight.
Yes, you can get sunburns on cloudy days. Sunburns are caused by ultraviolet rays, which are not blocked by clouds, only by sunscreen. Sunburns are usually worse on cloudy days because people do not realize they can get burned and do not wear enough sunscreen.
chlorosis-loss of the green colour caused by factors other than lack of sunlight
reflected sunlight