Ozone as concentrations in μg/m. The study of ozone concentration in the atmosphere started in the 1920s. The highest levels of ozone in the atmosphere are in the stratosphere, in a region also known as the ozone layer between about 10 km and 50 km above the surface (or between about 6 and 31 miles). However, even in this "layer", the ozone concentrations are only two to eight parts per million, so most of the oxygen there is dioxygen, O, at about 210,000 parts per million by volume. Ozone in the stratosphere is mostly produced from short-wave ultraviolet rays between 240
Sodium layer compensate for movements in the atmosphere. As a result, optical telescopes can perform much closer to their theoretical limit of resolution. The sodium layer was first discovered in 1929 by American astronomer Vesto Slipher. In 1939 the British-American geophysicist Sydney Chapman proposed a reaction-cycle theory to explain the night-glow phenomenon. Sodium layer The sodium layer is a layer of neutral atoms of sodium within Earth's mesosphere. This layer usually lies within an altitude range of above sea level and has a depth of about . The sodium comes from the ablation of meteors. Atmospheric sodium below this layer is normally