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Ultraviolet Light

Ultraviolet (UV) light is electromagnetic radiation that has a shorter wavelength than visible light, but longer than X-rays. When studying the effects of ultraviolet light on humans, it is often divided into UV-A or blacklight (380-315 nm), UV-B (315-280nm), and UV-C , or shortwave or germicidal (less than 280). All three forms of ultraviolet light damage skin and, potentially, genetic material, but longer wavelengths are less dangerous. The Sun emits all forms of ultraviolet light, but 99% is absorbed by the ozone layer.

Animals like birds, reptiles, and bees can perceive ultraviolet, and studies have revealed that certain fruit, flowers, and seeds are bright in ultraviolet light. Other things are made more visible in ultraviolet light such as the pattern in some birds' plumage and many types of animal urine. Glass is opaque to shorter wavelengths of ultraviolet light.

Ultraviolet light has many positive uses. It induces production of vitamin D in the skin and can treat psoriasis and vitiligo. Blacklights reveal invisible markings to prevent counterfeiting. Ultraviolet light carries data about distant stars and other celestial objects, and about tiny quantities of chemicals in labs. Because bugs see ultraviolet light, they are drawn to ultraviolet lights, and it's used by engineers to detect insulation flaws in electronic apparatus. Its most important application today may be in sterilization; it is a very effective germicide.

Web Resources On Ultraviolet Light

Ultraviolet Waves
Ultraviolet Light

Book Resources On Ultraviolet Light

Sunrays And Health: Every Day Use of Natural And Artificial Ultraviolet Light by Ronald Millar and E. E. Free
Ultraviolet Light and Fluorescent Minerals by Thomas S. Warren et. al

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