UV Rays: Whats the Difference?

As we all know, UV ray's are what we protect our skin from when we use sunblock before laying out in the back yard or go to the tanning salon. But just what are these ray's and how many of them are there?

There are three types of UV ray's. All can do damage to the skin, but in different degree's. The "UV" is for Ultraviolet....these are the invisible sun-rays that you don't see.

UVA -- longest wavelength - This is accountable for about 95% of the UV rays getting to Earth. It also get reach down deep through the skin. It also causes skin to age, and wrinkles, and cause skin cancer if not protected.

UVB -- medium wavelength -- This is an active UV, in that it cannot get through the surface of the skin. This is the one that allows you to tan and burn and increases the aging of the skin, and develop into skin cancer.

UVC -- shortest wavelength -- This is the most damaging UV, but most of it's rays don't even reach the Earth.

The level of UV rays depends mostly on how high the sun is, in the sky. It is the highest at mid-latitude during the summer and for a four hour period around the solar noon. You've heard it be said, that you shouldn't do much hard active activity around this time. That is because at this time, the sun's rays are in a direct path to the Earth. Early morning, or late afternoon is the best time for doing much of the outdoor activity if any needs done. During this time, the sun's rays are coming to Earth a an angle through the sky and more of the UV are absorbed so less reaches us.

The closer you are to the Equator of the Earth, the higher the UV levels will be. The UV rays have a shorter travel distance at the Equator. Less of the UV's are absorbed.

UV rays can also be reflected on on the surface of the Earth as well. Only 10% will be reflected on grass, soil and water, while sea foam accounts for a 25% increase of UV levels. Think you need to watch the UV levels just during the summer? Think again... Fresh snow in winter can be a great UV reflector, nearly doubling the UV exposure.

Clouds can play a big part in the UV levels. On a bright cloudless sunny day, that's when the levels are at their highest. But don't misjudge a overcast day with a cool breeze either. A long stay in the open shade can get you an unexpected tanning if the UV levels are high.

If you're real sensitive to the sun, don't be afraid to go outside.....use a good "broad spectrum" sunscreen for year-round use. Read labels, see if it says UVA/UVB protection.

Source:

World Health Organization - UV info

Ultraviolet Rays - what is it