Snow Blindness
Snow blindness is a painful condition, typically a keratitis, caused by exposure of unprotected eyes to the ultraviolet (UV) rays in bright sunlight reflected from snow or ice. This is especially a problem in polar regions and at high altitudes, as with every thousand feet (approximately 305 meters) increase in elevation, the intensity of UV rays goes up five percent. Snow blindness is akin to a sunburn of the cornea and conjunctiva, and may not be noticed for several hours from exposure.
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[...] sheets of white ice covering the Earth reflected most of the warming UV rays that heated the Earth during this period. Eventually, however, our old friends the volcanoes helped [...]
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