In London they were on display outside the Natural History Museum; and were subsequently exhibited outside City Hall for most of 2005, together with a giant world map on the ground showing where each photograph was taken. This is because the distance that particles can move without colliding with one another is large compared with the size of motions that cause mixing. In this layer ozone concentrations are about 2 to 8 parts per million, which is much higher than in the lower atmosphere but still very small compared to the main components of the atmosphere.

Main article: Atmospheric temperature Temperature trends in two thick layers of the atmosphere as measured between January 1979 and December 2005 by microwave sounding units and advanced microwave sounding units on NOAA weather satellites. However, ionization in the mesosphere largely ceases during the night, so auroras are normally seen only in the thermosphere and lower exosphere. a b Two recent reliable sources cited here have total atmospheric compositions, including trace molecules, that exceed 100%.ISBN 0-387-98746-0 , which rounds N 2 and O 2 to four significant digits without affecting the total because 0. The geological record however shows a continuous relatively warm surface during the complete early temperature record of Earth – with the exception of one cold glacial phase about 2. Various authorities consider it to end at about 10,000 kilometres (6,200 mi) [23] or about 190,000 kilometres (120,000 mi)—about halfway to the moon, where the influence of Earth's gravity is about the same as radiation pressure from sunlight. How Earth at that time maintained a climate warm enough for liquid water and life, if the early Sun put out 30% lower solar radiance than today, is a puzzle known as the " faint young Sun paradox". This rise in temperature is caused by the absorption of ultraviolet radiation (UV) from the Sun by the ozone layer, which restricts turbulence and mixing.

It contains the ozone layer, which is the part of Earth's atmosphere that contains relatively high concentrations of that gas. The above lying stratosphere can be seen at the horizon as a band of its characteristic glow of blue scattered sunlight.The depth of the planetary boundary layer ranges from as little as about 100 metres (330 ft) on clear, calm nights to 3,000 m (9,800 ft) or more during the afternoon in dry regions. Density is not measured directly but is calculated from measurements of temperature, pressure and humidity using the equation of state for air (a form of the ideal gas law). Main article: Mesosphere Afterglow of the troposphere (orange), the stratosphere (blue) and the mesosphere (dark) at which atmospheric entry begins, leaving smoke trails, such as in this case of a spacecraft reentry. Meteors begin to glow in this region, though the larger ones may not burn up until they penetrate more deeply. The images are taken from the Deep Space Climate Observatory (DSCOVR) and show Earth as it rotates during a day.