Editing Troposphere (section)

===Composition===
The Earth's planetary atmosphere contains, besides other gases, water vapour and carbon dioxide, which produce carbonic acid in [[rain water]], which therefore has an approximate natural pH of 5.0 to 5.5 (slightly acidic).   (Water other than atmospheric water vapour fallen as fresh rain, such as fresh/sweet/potable/river water, will usually be affected by the physical environment and may not be in this pH range.) Atmospheric water vapour holds suspended gasses in it (not by mass), 78.08% [[nitrogen]] as N<sub>2</sub>, 20.95% [[oxygen]] as O<sub>2</sub>, 0.93% [[argon]], trace gases, and variable amounts of condensing water (from [[saturated water vapor]]). Any carbon dioxide released into the atmosphere from a pressurised source combines with the carbonic acid water vapour and momentarily reduces the atmospheric pH by negligible amounts. Respiration from animals releases out of equilibrium carbonic acid and low levels of other ions. Combustion of hydrocarbons which is not a chemical reaction releases to atmosphere carbonic acid water as; saturates, condensates, vapour or gas (invisible steam). Combustion can releases particulates (carbon/soot and ash) as well as molecules forming nitrites and sulphites which will reduce the atmospheric pH of the water slightly or harmfully in highly industrialised areas where this is classed as air pollution and can create the phenomena of acid rain, a pH lower than the natural pH5.56. The negative effects of the by-products of combustion released into the atmospheric vapour can be removed by the use of scrubber towers and other physical means, the captured pollutants can be processed into a valuable by-product. The sources of atmospheric water vapor are the bodies of water (oceans, seas, lakes, rivers, swamps), and vegetation on the [[planetary surface]], which humidify the troposphere through the processes of [[evaporation]] and [[transpiration]] respectively, and which influences the occurrence of weather phenomena; the greatest proportion of water vapor is in the atmosphere nearest the surface of the Earth. The temperature of the troposphere decreases at high [[altitude]] by way of the [[Inversion (meteorology)|inversion layer]]s that occur in the [[tropopause]], which is the atmospheric boundary that demarcates the troposphere from the [[stratosphere]]. At higher altitudes, the low air-temperature consequently decreases the [[saturation vapor pressure]], the amount of atmospheric water vapor in the upper troposphere.