Purchase Effective Sunblocks and Sunscreens
The sun is responsible for our very existence here on earth. Its light is the fuel for photosynthesis: the process by which plants create their energy and we, in turn, depend on the plants for food and oxygen. The sun's infrared rays keep us warm and its visible rays give us the "light" to see by. The sun's ultraviolet radiation is also useful but, at the same time, its very dangerous to us. Ultraviolet radiation (UVR) is the cause of most skin cancers, many cataracts and 90% of visible aging ( the changes we see in our skin as we get older).
UVR is divided into 3 different bands: UVA, UVB, UVC. Virtually all of UVC is filtered out by our atmosphere so that none actually reaches the earth's surface. UVB and UVA both reach the earth in significant amounts.
UVB is "stronger" than UVA having a greater ability to cause skin damage. There is , however, about 100 times as much as UVA as UVB so that, despite being weaker, UVA is still dangerous.
Some other UVR facts are:
- UVR is strongest between 10:00AM and 2:00PM.
- Clouds filter some but not most of the UVR so its still possible to get burned on a cloudy day.
- Some ground surfaces such as sand and snow reflect most of the UVR. For instance snow can reflect as much as 80% on the incident UVR.
- Water actually reflects very little UVR.
- For every 1000 feet increase in altitude the UVR increases by 4%.
