What do UVA/UVB stand for?

Answers:
The UV in UVA/UVB/UVC means ultra violet light. The ABC are different wavelenghts of the light. Read an excerpt below from the article on the link for more explanation:
Sunlight has a profound effect on the skin causing premature skin aging, skin cancer, and a host of skin changes. Exposure to ultraviolet light, UVA or UVB, from sunlight accounts for 90% of the symptoms of premature skin aging. Many skin changes that were commonly believed to be due to aging, such as easy bruising, are actually a result of prolonged exposure to UV radiation.
What is UV?
The sun gives off ultraviolet radiation that we divide into categories based on the wavelength. UVC - 100 to 290 nm
UVB - 290 to 320 nm
UVA - 320 to 400 nm UVA was once thought to have a minor effect on skin damage, but now studies are showing that UVA is a major contributor to skin damage. UVA penetrates deeper into the skin and works more efficiently. The intensity of UVA radiation is more constant than UVB without the variations during the day and throughout the year. UVA is also not filtered by glass.

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It has something to do with the type of ultraviolet rays that are emitted from the sun--and are bad for your skin. I forget, but each one causes a certain damage to the skin.

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UVA is UltraViolet typeA. UVB is UltraViolet type B(Sun rays)

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Ultraviolet A and Ultraviolet B. The terms are often used when talking about how skin is affected by UV rays.
UVB is what causes sunburn, and its what most sunscreens block best. UVA is what causes the most skin damage, including premature aging and cancer. :(There is a sunscreen that's been on the market in Europe for some time that does a good job of blocking both kinds, and its recently been approved for sale in the US. If that's where you are, you should start seeing it soon as an ingredient in sunscreens. Its called 'Parsol'.

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Ultra Violet A(400鈥?15 nm), and Ultra Violet B (315鈥?80 nm)
Both are rays of light with different wavelengths.
UVA is light we see, and UVB is invisible, and responsible for vitamin synthesis. Both are damaging to the body, though it is harder to block UVA rays, due to it's "dark light" quality.

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UVA
Ultraviolet Category AUVB
Ultraviolet Category BUVA represents the lower range of UV and UVB is the higher range.
UVB gives more damage.

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Ultra Violet rays are diveded into 3 groups according to their wavelength/frequancy UV-A,B and C. UV-A has the longest wavelength and therefore less harmfull. UV-C has the largest frequancy so the cary more energy %26 therefore the most harmfull. for exact figurs see.

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UVA light is also known as "dark-light" and, because of its longer wavelength, can penetrate most windows. It also penetrates deeper into the skin than UVB light and is thought to be a prime cause of wrinkles.
UVB light can cause skin cancer. The radiation excites DNA molecules in skin cells, causing covalent bonds to form between adjacent thymine bases, producing thymidine dimers. Thymidine dimers do not base pair normally, which can cause distortion of the DNA helix, stalled replication, gaps, and misincorporation. These can lead to mutations, which can result in cancerous growths. The mutagenicity of UV radiation can be easily observed in bacteria cultures. This cancer connection is one reason for concern about ozone depletion and the ozone hole.
Using the ultraviolet light (Wood's lamp), your doctor may be able to confirm a diagnosis of fungal infection or bacterial infection. Your doctor may also be able to gain insight into the cause of light- or dark-colored spots on your skin.
Please see the webpages for more details on Ultraviolet and Wood's lamp.

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