Radiant Energy

Radiant energy exists in a range of wavelengths that extends from radio waves that many be thousands of meters long to gamma rays with wavelengths as short as a million-millionth (10-12) of a meter.

Of particular importance to living things are

Ultraviolet light (UV) can be further subdivided into

The shorter wavelengths of ultraviolet can be absorbed by DNA and damage it — causing mutations.

X-rays and gamma rays also damage DNA by generating ions within the cell. Thus these wavelengths represent ionizing radiation.

Link to a discussion of ionizing radiation.

Light makes possible a number of essential functions in living things:

Approximately one-half of the energy reaching the earth from the sun is light; that is, it is within the visible portion of the spectrum. The remainder arrives as heat and a small amount of ultraviolet light (which can, however, have a large effect on the aging of skin and the development of skin cancer).

Link to more on the input of the sun's energy on earth.
Link to a discussion of the relationship between ozone in the stratosphere and the amount of UV-B reaching the earth.
Link to a discussion of radiation and cancer.

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5 April 2012