Homogenitus (cloud)

A homogenitus, anthropogenic or artificial cloud, is a cloud induced by human activity. Although generally clouds covering the sky have only a natural origin, from 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. These new atmospheric conditions can thus enhance cloud formation.

Various methods have been proposed for creating and utilizing this weather phenomenon. Experiments have also been carried out for various studies. For example, Russian scientists have been studying artificial clouds for more than 50 years. But by far the greatest number of anthropogenic clouds are airplane contrails (condensation trails) and rocket trails.

Three conditions are needed to form a cloud:

The current use of fossil fuels enhances any of these three conditions. First, fossil fuel combustion generates water vapor. Additionally, this combustion also generates the formation of small solid particles that can act as condensation nuclei. Finally, all the combustion processes emit energy that enhance vertical upward movements.

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. Each cloud has a name in Latin and clouds are classified according to its genus, 'species, variety :

Further terms can be added to describe the origin of the cloud. Homogenitus is a suffix that signifies that a cloud originates from human activity. For instance Cumulus originated by human activity is called Cumulus homogenitus and abbreviated as CUa. If a homogenitus cloud of one genus changes to another genus type, it is termed a homomutatus cloud.

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