Anthropogenic cloud
Although most clouds covering the sky have a purely natural origin, since the beginning of the Industrial Revolution, the use of fossil fuels and water vapor and other gases emitted by nuclear, thermal and geothermal power plants yield significant alterations of the local weather conditions.
Despite all the processes involving the combustion of fossil fuels, only some human activities, such as, thermal power plants, commercial aircraft or chemical industries modify enough the atmospheric conditions to produce clouds that can use the qualifier homogenitus due to its anthropic origin.
The International Cloud Atlas published by the World Meteorological Organization compiles the proposal made by Luke Howard at the beginning of the 19th century, and all the subsequent modifications.
Despite the fact that the three genera of high clouds, Cirrus, Cirrocumulus and Cirrostratus, form at the top of the troposphere, far from the earth surface, they may have an anthropogenic origin.
Exhaust products from the combustion of the kerosene (or sometimes gasoline) expelled by engines provide water vapor to this region of the troposphere.
Depending on the atmospheric conditions at the upper part of the troposphere, where the plane is flying, these high clouds rapidly disappear or persist.
When the air is dry and stable, the water rapidly evaporates inside the contrails and can only observed up to several hundreds of meters from the plane.
[citation needed] The lowest part of the atmosphere is the region most influenced by human activity, through the emission of water vapor, warm air, and condensation nuclei.
When the atmosphere is stable, the additional contribution of warm and moist air from emissions enhances fog formation or produces layers of Stratus homogenitus (Sth).
Finally, the large, towering Cumulonimbus (Cb) presents such a great vertical development that only in some particular cases can they be created by anthropic causes.
[11] Plans to create artificial clouds over soccer tournaments in the Middle East were suggested in 2011 as a way to help shade and cool down Qatar's 2022 FIFA World Cup.
