When people think about UV light they usually imagine lying out on the beach, the sun shining high above, searing the sky and surf and slowly roasting them to a delectable lobster red. With the sun's force tempered by the Winter, people tend to forget about the dangers of UV, think that the cloud cover or lowered temperatures mean that their skin is safe, that there's no risk of burning or worse. This is wrong, and since each passing year brings about further erosion of the ozone layer's protection, it is especially important to learn about the realities of UV light, and how we can best protect ourselves from its pervasive threat.

What is UV light? Simply put, it's electromagnetic radiation with a wavelength that's shorter than that of visible light, and longer than x-rays. Visible light, UV rays, x-rays-all of these are just names for different wavelengths of electromagnetic rays. It's called ultra-violet because these frequencies are higher than the wavelengths that we humans identify as violet. There are five kinds of UV light, but the first two, Vacuum UV and Far UV are both completely absorbed by the atmosphere.

UVC is also rarely found on our planet due to its absorption by the atmosphere, but is sometimes used in germicidal lamps due to its ability to kill germs. UVC is absorbed by the outer, dead layers of our skin, and can cause corneal burns (commonly termed welders' flash) and snow blindness, a severe sunburn of the face. Though extremely painful, UVC burns usually clear up in a couple of days.

UVB is the most dangers of the commonly encountered forms of UV. It has enough energy to wreak photochemical havoc on our cellular DNA, but not enough to be absorbed by the atmosphere like UVC. UVB is needed by our skin to generate Vitamin D, but too much exposure can cause sunburn, cataracts and can lead to skin cancer. People who work outside are at the most risk of these dangers, and cloud cover is not enough protection to block UVB.

UVA is the most commonly found form of UV, and is responsible for the tanning effect we see in our skin after time spent in sunlight, and can cause sunburn if exposure is excessive. The atmosphere does very little to block this kind of UV, and it's needed to help generate Vitamin D. However, too much exposure can cause our skin to grow tough, hard, and wrinkled. It can also suppress the immune system and cause the creation of cataracts. Most tanning booths and phototherapy use this kind of UVA.

UV light has too much energy for us. While visible light does little to our skin, UV is to jazzed up. They create heat in the same way that rubbing your hands does-but instead of simply causing the molecules of our skin to vibrate they can actually knock electrons right out of the atoms, or cause molecules to split. This results in a change of the chemical structure of the molecule. This change is especially dangers to living organisms, as changing the composition of your DNA can lead to mutations, which can lead to cancer.

So be careful with exposure to the sun. Even during the winter it's likely that you're being exposed to UVA and UVB, and with skin cancer rates rocketing, it's critical that we take care of ourselves by reducing time spent in the sun and being sure to protect our skin from UV when we're out and about.