DRAW Blog

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Clouds, Cloud Types and Abbreviations

Victoria Slonosky, March 13 2019

Clouds or the lack of, are an ever present part of our skyscape. It is no wonder then that when the classification of the world around us began during the 18th century Enlightenment, with Carl Linne in Sweden developing the binomial system of plant classification (still used today for all living things) that the classification of clouds wouldn't be far behind. The classification began in the early 19th century with Luke Howard.

Luke Howard was a Quaker chemist who spent hours as a boy watching the clouds. He was among the first to realize that clouds had a limited number of distinct types, rather than endlessly drifting from one shape to the next (Jean-Baptiste Lamarck was another who tried to classify clouds by type and height). He based his Latin cloud names on the typical shapes and heights of the clouds. Cumulus clouds are heap-like, stratus clouds by definition and have some form of precipitation falling from them. As they were based on Latin, Howard’s cloud types were able to be used internationally since he first devised them in 1817.

Howard gave his first lecture on cloud types in London in 1802, when he proposed that there were three main types of clouds: Cirrus, Cumulus, and Stratus. He recognized also that clouds morphed from one type to another, often in recognizable ways as the weather changed. For example, cumulus clouds could spread and merge into a stratus layer. He proposed that the basic cloud formations reflected the physical process by which the clouds were formed, such as cumulus clouds being formed by convection, which turned clouds from mysterious, ever-changing entities into physical sciences which could be studied and related to weather such as participation. In a way, we could say that the classification of clouds launched the scientific field of meteorology.

frontispiece of Essay on the Modification of Clouds

Thunderclouds gathering - frontispiece of Essay on the Modification of Clouds, 3rd Ed. Luke Howard, 1865

When writing down the observations for clouds in ledgers such as the ones which DRAW is transcribing from, using the full name of a cloud could be cumbersome. Clouds as a result have two letter abbreviations, such as Ci for Cirrus. They can be combined, such as when there is a layer of cumulus clouds to form Cumulo-stratus, Cu-St, or the most impressive of all, the towering thunderstorm clouds which all the way through the atmosphere to the top of the troposphere, Cumulonimbus, CuNi. All clouds with precipitation falling from them are nimbus clouds, so if while transcribing you see an entry for nimbus, check to see if there’s also some precipitation, usually in the form of rain or snow in the same observation time!

If you’re interested in reading more about the history of cloud classification, check out the free e-book of Luke Howard’s Essay on the Modification of Clouds (1865) available here. You can also check out our Meteorological Observations page for a full list of cloud types and their abbreviations!

tags: #weather history

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Clouds, Cloud Types and Abbreviations