Energy from the sun reaches the earth as visible, infrared, and ultraviolet (UV) rays. Exposure to UV rays can cause numerous health problems, such as sun burn, skin cancer, skin aging, and cataracts, and can suppress the immune system. A scale ranging from 0 to 16, used in estimating the risk for sunburn that an unprotected fair-skinned person would have if exposed to the ultraviolet radiation
temperature
MED dose leading to sunburn.A person with Type II skin type might choose 0.75 MED as the maximum for the day
| Skin Type | Skin Color | Tanning & Sunburning |
| I | White | Always burns easily, never tans |
| II | White | Always burns easily, tans minimally |
| III | Light Brown | Burns moderately, tans gradually |
| IV | Moderate Brown | Burns minimally, tans well |
| V | Dark Brown | Burns rarely, tans profusely |
| VI | Black | Never burns, deep pigmentation |
Out of 100% sun radiation: 30% is transfered back to space, 70% absorbed into clouds, atmosphere, land and sea.
