But what do each of them mean?
- UVA rays are linked to long-term skin damage such as wrinkles, but they are also thought to play a role in some skin cancers.
- UVB rays have slightly more energy than UVA rays. They can damage skin cells' DNA directly, and are the main rays that cause sunburns. They are also thought to cause most skin cancers.
- UVC rays have more energy than the other types of UV rays, but they don't get through our atmosphere and are not in sunlight. They are not normally a cause of skin cancer.
The darkening or reddening of our skin is actually a defense mechanism to these harmful rays. Our skin cells produce something called melanin to absorb the UV light and dissipates it as heat. Melanin is sent to protect us when our body senses there may be skin damage occurring.
Too much exposure to these unhealthy rays can cause our skin cells to mutate becoming problem cells like cancer. According to the Skin Cancer Foundation, the chance for the deadliest form of skin cancer, called melanoma, doubles for someone who has had five or more sunburns.
The American Cancer Society says the strength of the UV rays reaching the ground depends on a number of factors, such as:
- Time of day: UV rays are strongest between 10 a.m. and 4 p.m.
- Season of the year: UV rays are stronger during spring and summer months.
- Distance from the equator (latitude): UV exposure goes down as you get further from the equator.
- Altitude: More UV rays reach the ground at higher elevations.
- Cloud cover: The effect of clouds can vary. Sometimes cloud cover blocks some UV from the sun and lowers UV exposure, while some types of clouds can reflect UV and can increase UV exposure. What is important to know is that UV rays can get through, even on a cloudy day.
- Reflection off surfaces: UV rays can bounce off surfaces like water, sand, snow, pavement, or grass, leading to an increase in UV exposure
The UV index is something you may see our Storm Center 7 team show in reference to how strong the sun is on any given day. The Environmental Protection Agency created the UV Index, and it ranges from 1 to 11+. The higher the index, the greater the intensity of the UV rays and the potential for sunburn or skin damage.