Stratosphere around at midlatitudes, and at about at the poles. Temperatures range from an average of near the tropopause to an average of near the mesosphere. Stratospheric temperatures also vary within the stratosphere as the seasons change, reaching particularly low temperatures in the polar night (winter). Winds in the stratosphere can far exceed those in the troposphere, reaching near in the Southern polar vortex. The mechanism describing the formation of the ozone layer was described by British mathematician Sydney Chapman in 1930. Molecular oxygen absorbs high energy sunlight in the UV-C region, at wavelengths shorter than about 240 nm. Radicals produced
UV filter offer some protection against lens contamination while minimising the inherent additional distortion. However, in photography, the term "UV filter" can be also misused as a filter that passes UV light while blocking other wavelengths in the light spectrum, in the same way the term "IR filter" is also sometimes misused. The correct names for such filters though, are "UV pass filter" and "IR pass filter". This is a very specialized area in photography. Excessive UV radiation can expose humans to various risks, including skin diseases such as sunburns, photo-aging, and skin cancers. UV radiation can be classified as UVA (320-400