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Condensation Trails (‘contrails’) – like cirrus clouds, contrails are composed of descending ice crystals formed by the sudden condensation of water vapour from aircraft exhaust at 35,000 feet. In warmer or drier air (settled conditions) contrails are very short-lived but in cold moist air they can last for long periods, indicating rain within 72 hours. Distrails (‘dissipation trails’) occur when an aircraft passes through natural cirrus or altostratus, overloading the cloud with moisture which falls out, leaving gaps in its wake. There is a whole science evolving around the study of contrails, and how they might influence global warming and our future climate as air travel increases. |
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Pyrocumulus Cloud – this cumuliform cloud is formed by convection of warm moist air in stable conditions from ground-level bush fires, stubble-burning or volcanoes. |
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‘Fumulus’ Cloud – this is a variety of pyrocumulus cloud formed above industrial cooling towers such as those found at power stations. |