Why does the sun make our skin brown & our hair lighter ?

ultra violet light penetrates the skin, causing different reactions,.uva rays are the tanning rays and uvb arte the burning rays.they are more intense.the sun emits more uvb rays which are more intense.when the skin is exposed to the uvb light more melanin (tanning pigment)is produced by cells called melanocytes.melanin is carried to the upper layer of the skin. the melanin is then oxidised , tanning the skin in the process.i had to learn this for my work as i apply spray tan to my customers.

to explain this you have to know a lot of things.i'am afraid i can't answer your question