The sun emits light onto the earth, some of which is in the form of invisible UV radiation. These rays induce tanning, burning, and other skin damage when they reach the skin. UVA rays induce skin aging and wrinkling, as well as contributing to skin malignancies like melanoma (the most dangerous form of skin cancer). UVB rays are responsible for sunburns and other acute effects on the skin. People who spend a lot of time in the sun are at risk for skin cancers; those diseases can be fatal if not treated promptly. In addition to harming the skin, the sun's energy reaches the earth's atmosphere where it causes clouds to form and evaporate, which leads to global warming. Without this cloud cover, more sunlight would be absorbed by the oceans, leading to more heat-induced oceanic activity like sea level rise and ocean acidification. People need protection from the sun's harmful rays throughout their lives. You should avoid direct exposure to the sun, especially between 10 a.m. and 4 p.m., when your body temperature is at its highest. Wear sunscreen with a SPF of at least 15 during these hours. Even if you don't get sunburn, you're still at risk for other health problems like skin cancer. Avoid walking through deep sand or gravel areas when possible. These areas will burn your feet and legs without giving you any protection against the sun. Children particularly need protection from the sun.