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
Layer by Layer Layer by Layer The Layer by Layer method is a method of solving the 3x3x3 Rubik's Cube. Many beginners' methods use this approach, but it also forms the basis of the CFOP speedcubing technique. The Layer by Layer Method was pioneered by David Singmaster in his 1980 book "Notes on Rubik's "Magic Cube"". The same idea was adopted by James G. Nourse in his "The Simple Solution to Rubik's Cube" which became the bestselling book of 1981, and similar approaches could be found in Don Taylor's "Mastering Rubik's Cube" and Cyril Östrop's "Solving the Cube" from the same era. It