Light is made of both waves and particles. The rate at which these waves oscillate determines what type of wave it is. Ultraviolet waves (UV waves) are waves that are shorter than violet light--the shortest light wave humans can detect with our eyes. Ultraviolet waves are between 100 and 4000 angstroms (10-400 nanometers). This is shorter than visible light but longer than X-rays and gamma rays.
The shorter the wave in the spectrum, the more energy it has and the faster it oscillates. The more energy a wave has, the more dangerous it is to humans. The higher energy means that the waves can penetrate further into the human body and cause more damage. Ultraviolet, X-rays, and gamma rays are all waves that are shorter than violet on the light spectrum. While all three can be damaging to humans, ultraviolet waves have become the most well-known.
The most harmful ultraviolet waves are kept out by the Earth's atmosphere, but some are able to sneak in. This can be both a good or bad thing since ultraviolet waves are both helpful and harmful. Some animals, like bees, can detect UV light and see special patterns in flowers that lead them to the source of the nectar. In addition, the waves can also give scientists a different view of the universe. By using specialized cameras and equipment, scientists are able to study the sun, stars, as well as different objects on our own planet.
Another benefit to ultraviolet light is its ability to sterilize. UV waves are used in air and water purifiers as a way to eradicate bacteria and viruses. The waves are also instrumental in our bodies' production of vitamin D. When UV waves hit the skin, they stimulate the vitamin's production. While it is true that UV waves contribute to vitamin D production, it is important not to overexpose yourself to any form of ultraviolet light.
One of the most common forms of damage caused by UV waves is sunburn. When the waves hit the skin, they can damage or kill skin cells. Over time, the overexposure to UV waves can also lead to skin cancer. Since sunburn is caused by ultraviolet waves, it is even possible to get sunburned on a cloudy day; wearing the appropriate protection all the time is important. Limiting the exposure to ultraviolet waves over a lifetime can help people avoid those disastrous side effects.