UV Radiation - Invisible energy

UV (ultraviolet) radiation is an invisible part of the sun's energy. There are different kinds of ultraviolet rays based on their wavelength. Two types that reach the earth are UVA and UVB. UVA rays go deeper into the skin, causing wrinkles and skin aging. UVB rays cause burning and blistering on your skin.

Effects of UV radiation; Good news & Bad news

The sunlight is the source of the all life on earth. It lights up the earth and gives the solar energy to plants and animals to live. Also it assists in the production of vitamin D in skin cells. This vitamin is essential for the growth and development of healthy bones.

Doctors tell us that a small amount (10 - 15 minutes per day) of sun exposure is good for health, but sun overexposure can lead to a number of serious health problems, including malignant melanoma, other skin cancers, eye cataracts, weakening of the immune system, and premature aging of the skin. With reduced ozone protection, increased levels of UV radiation are reaching the earth's surface.

Factors influencing UV Radiation

Time of day: When the sun is highest in the sky, UV radiation is intense.

Season of year: The sun is strong in summer, intermediate in spring and fall, and lowest in winter. UV rays are also reflected by sand and water, even in winter, sun overexposure can occur because ice and snow reflect a large amount of UV radiation.

Weather conditions: It is true that there is less UV radiation on a cloudy day, but clouds cannot absorb one hundred percent of the harmful rays. Sometimes clouds increase the UV radiation through reflecting it.

Latitude: Generally, the further away from the equator, the less amount of UV radiation.

Altitude: The amount of UV radiation increases significantly with altitude because there is less atmosphere to absorb the UV radiation.

Ozone conditions: Thicker ozone provides better protection from UV radiation and the thickness of the ozone layer varies by season and latitude.

UV index

The UV index, developed by the National Weather Service and the Environmental Protection Agency, is a new component for local weather forecasts that predicts tomorrow's likely levels of exposure to UV radiation and also indicates the degree of caution you should take outdoors. The UV index predicts UV levels on a 0 to 10+ scale. The lower number means less exposure.

More information on UV index, what it is, how it is calculated, and UV crossword puzzle, is provided by the Environmental Protection Agency Web site.


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