The ultraviolet rays reflected from the snow are almost all that are present in sunlight. Nature Magazine, pg 144, 3/30/1911
Ultraviolet frequencies produce vitamin D. Birren, Faber; "Color Psychology and Color Therapy"; New York, University Books, 1961
According to multiple sources (NASA, FDA, and others) here are the wavelengths of the UVA, UVB and UVC regions:
Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than x-rays?, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV. It is so named because the spectrum consists of electromagnetic waves with frequencies higher than those that humans identify as the color violet.
UV light is found in sunlight and is emitted by electric arcs and specialized lights such as black lights. As an ionizing radiation it can cause chemical reactions, and causes many substances to glow or fluoresce?. Most people are aware of the effects of UV through the painful condition of sunburn, but the UV spectrum has many other effects, both beneficial and damaging, on human health.
|Name||Abbreviation||Wavelength||range in nanometers||Energy per photon|
|Ultraviolet A, long wave, or black light||UVA||400 nm||320 nm||3.10 3.94 eV|
|Near||NUV||400 nm||300 nm||3.10 4.13 eV|
|Ultraviolet B or medium wave||UVB||320 nm||280 nm||3.94 4.43 eV|
|Middle||MUV||300 nm||200 nm||4.13 6.20 eV|
|Ultraviolet C, short wave, or germicidal||UVC||280 nm||100 nm||4.43 12.4 eV|
|Far||FUV||200 nm||122 nm||6.20 10.2 eV|
|Vacuum||VUV||200 nm||10 nm||6.20 124 eV|
|Extreme||EUV||121 nm||10 nm||10.2 124 eV|
Note: nm means nanometer (400 nm = 400 x 10-9 meters or 0.0000004 meters) (source unknown)
Page last modified on Sunday 14 of March, 2010 04:35:22 MDT