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 nm), UVB (290-320 nm) and UVC (200-280 nm ). Ultraviolet absorbing compounds are the active ingredients of sunscreen products and other personal care products (e.g. lipsticks, shampoos, hair sprays, body washes, toilet soaps, and insect repellents). Chemical filters are generally used in combination in order to get sufficient protection against UV. They protect humans from the serious effects of UV radiation by absorbing, reflecting or scattering it. The reflection and scattering effecst are done by physical UV filters which are inorganic UV filters such as titaniumdioxide (TiO) and zinc oxide (ZnO). Absorption is accomplished by organic UV filters which are