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The ultraviolet spectrum consists of wavelengths that are shorter than visible light. Unless they are blind, humans can see visible light. There are however, rays of light that even humans with healthy eyes cannot see. These rays are part of the ultraviolet spectrum.
Ultraviolet, sometimes abbreviated UV, means beyond violet. This name is appropriate because violet is recognized as the shortest visible wavelength. Light that is ultraviolet is even shorter and, therefore, invisible to humans.
The ultraviolet spectrum can be easier to understand by visualizing a bar. If a person follows the length of that bar, she may think that she can see from the beginning to the end of it. The ultraviolet spectrum can be represented by an extension of the bar that continues but is invisible.
Natural UV waves are produced by radiation from the sun. Many of these rays do not enter human’s living environment because they are blocked by the ozone layer. This is a mixture of gases that act as Earth’s protective barrier.
Many products that offer UV protection claim to protect against various types of ultraviolet wavelengths. The ultraviolet spectrum is often divided into three parts. These can also be explained using the earlier bar example.
The ultraviolet light closest to what the person believes is the end of the bar is called near ultraviolet, or UVA. Beyond that is a group of wavelengths that compose the far ultraviolet segment. These may be referred to a UVB rays. Still farther beyond, there is a portion of the spectrum known as extreme ultraviolet, or UVC. This is believed to be the most energy intensive and dangerous segment of the ultraviolet spectrum.
Waves from the ultraviolet spectrum are not detected by human eyes, but they do affect human health. Some of the effects are harmful and some are beneficial. For example, humans need vitamin D. It is essential to calcium production and cell health. UVB is generally necessary for a human to produce a healthy amount of this vitamin.
On the contrary, too much exposure to UV waves can be harmful. Many people have experienced sunburn. Although this is often painful, it may be considered mild damage compared to what is possible. Various types of skin cancer can also result from excessive UV exposure. Eye damage is also possible.
Some people use special products to protect themselves from exposure to rays from the ultraviolet spectrum. Such products include glasses with specially coated lens and sunblock lotions. Other people intentionally expose themselves to UV waves to impact their skin color. For this, they typically use items such as tanning beds and sun tan lotions.