for evaluating the intensity of UV radiation
The UV Index indicates the intensity of UV radiation when it reaches the Earth's surface.
The higher the UV Index, the higher your risk of skin damage.
The UV Index varies depending on several factors:
The position of the sun: The higher the sun is in the sky, the more intense the radiation. Intensity varies on the time of day but peaks between 10am and 2pm, and is at it's peak at "Solar Noon"Altitude : The higher you are, the more intense UV radiation becomes.Latitude : UV radiation intensifies the closer you are to the equator.Cloud cover : Cloud cover does not protect from UV radiation.Reflection : UV rays are reflected with more or less intensity depending on the surface.
Grass: 3% of UV rays are reflected
Water: 5% to 20%