A research was conducted to find out about ultraviolet rays. The focus of this was to answer the question: What are ultraviolet rays? In 1801, Johann Ritter conducted an experiment, to prove there was a light beyond violet. Because photographic paper would turn black faster in blue light rather than red light, he exposed the photographic paper to light beyond violet. The paper turned black which proved the existence of light beyond violet-ultraviolet light. A light beyond the visible spectrum.
Ultraviolet rays are the sunlight that reaches Earth. There are two types of ultraviolet rays UV-A and UV-B. UV-A is the sunlight that comes down in long waves. UV-A rays dig deep into the dermis, the thickest layer of skin and can cause a change in skin texture, wrinkling, or put you at a risk for cancer. UV-B rays can burn your skin. The intensity of UV-B rays varies by season, location and time of day but they are the most intense between the hours of 10 AM and 4 PM. There is also another type of ray which is the shortest and strongest (UV-C), but luckily it is absorbed by the ozone layer and almost never reaches Earth.
There are many factors that influence the variability of UV radiation. UV levels are constantly changing. It all depends on the suns position in the sky, the thickness of the ozone layer, clouds and the weather. Clouds both have a positive and negative effect on UV levels. For example, clouds can deflect UV rays into space. However, clouds may also increase UV levels. This can happen when the sun is not blocked by clouds, but the clouds in the area of the sun reflect additional rays to the ground. Altitude also has an effect on UV levels. The higher you are, the greater the UV level is because of the thinner atmosphere. Snow, sand, and water can also reflect UV rays. Another factor is that the closer you are to the equator; the more UV rays you are exposed to. This is because, near the equator, the ozone layer is very thin and is not able to absorb as much UV rays.
