A scale for
Evaluating the riskw
Caused by UV radiation
The uv index expresses the intensity of UV radiation when it reaches the Earth's surface.
The higher the UV index, the higher the risk of skin and eye lesions.
It varies according to several factors:
- The Sun's position : the higher the position of the Sun in the sky, the more intense the radiation. This varies according to time of day. Intensity peaks between 11 am and 4 pm; this is called "solar noon".
- Altitude : the higher we are, the more intense UV radiation becomes.
- Latitude : UV radiation intensifies the closer we get to the equator.
- Cloud cover : the denser the cloud cover, the more intense UV radiation becomes.
- Reflection : UV rays are reflected with more or less intensity depending on the surface, which emphasizes how dangerous they are.
Grass: 3% of UV rays are reflected.
Water: 5% to 20%.