Ultraviolet (UV) radiaton is the source that causes the tanning and burning of our skin. Ultraviolet light is a part of the electromagnetic spectrum. The electromagnetic spectrum is the name that scientists gave a group of specific radiaton types. The largest sources of UV radiation include the sun, and the stars. Lucky for us, we are protected from excessive amounts of UV radiation by a chemical called ozone. A layer of ozone in the atmosphere prevents most UV rays from reaching the Earth.
- There are two types of UV radiation that reach Earth's surface, UV-A and UV-B. UV-A radiates at longer wavelengths (320-400nm*), while UV-B radiates at shorter wavelengths (290-320nm). UV-A helps form nessisary Vitamin D in the skin, but it also can burn skin, and cause cataracts in the eyes. UV-B radiation can cause changes in DNA molecules. These changes often result in enzymes not being able to "read" the DNA code on the molecule, which means that cells can die.
*nm=nanometers, or a billionth of a meter
This picture shows a damaged DNA molecule.
While everyone needs to be exposed to some UV rays in order to recieve the essential Vitamin D, excessive sun exposure can be potentially dangerous, meaning that even tanning isn't safe. Obviously, UV radiation cant be avoided, given that its main source is the sun, but you should definately be aware of the time that you spend in the sun. So next time you take that relaxing trip to the beach, load up on the sunscreen, dig out that ugly sun hat, and don't forget that beach umbrella.
(Courtesy of Google images)
Works Cited
Allen, Jeannie. “Ultraviolet Radiations:How it Affects Life on Earth.” Earth Observatory 6 Sept. 2001: n. pag. Web. 20 Mar. 2010. http://earthobservatory.nasa.gov/Features/UVB/.
Lujan, Barbara, and Ronald White. “Electormagnetic Spectrum.” NASA. HEASARC, 3 Feb. 2010. Web. 17 Mar. 2010. http:http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html.
Sparling, Brien. “Ultraviolet Radiation.” NAS. NASA, 30 May 2001. Web. 19 Mar. 2010. http://www.nas.nasa.gov/About/Education/Ozone/radiation.html.
Allen, Jeannie. “Ultraviolet Radiations:How it Affects Life on Earth.” Earth Observatory 6 Sept. 2001: n. pag. Web. 20 Mar. 2010. http://earthobservatory.nasa.gov/Features/UVB/.
Lujan, Barbara, and Ronald White. “Electormagnetic Spectrum.” NASA. HEASARC, 3 Feb. 2010. Web. 17 Mar. 2010. http:http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html.
Sparling, Brien. “Ultraviolet Radiation.” NAS. NASA, 30 May 2001. Web. 19 Mar. 2010. http://www.nas.nasa.gov/About/Education/Ozone/radiation.html.