Glossary : Ultraviolet Radiation
The energy range just beyond the violet end of the visible spectrum.
Although ultraviolet radiation constitutes only about 5 percent of the
total energy emitted from the sun, it is the major energy source for the
stratosphere and mesosphere, playing a dominant role in both energy
balance and chemical composition.
Most ultraviolet radiation is blocked by Earth's atmosphere, but some
solar ultraviolet penetrates and aids in plant photosynthesis and helps
produce vitamin D in humans. Too much ultraviolet radiation can burn the
skin, cause skin cancer and cataracts, and damage vegetation.
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