DRAW Blog

Exploring weather and all it entails

International Communication: Weather Symbols

Victoria Slonosky, March 27th 2019

Welcome to another DRAW Blog post! This week we will be looking at the why and how of weather symbols.


While transcribing you may have come across little symbols used to depict different types of weather, rather than writing. It was one of the most difficult challenges we faced in designing our interface in fact. We can’t just ask our citizen scientists to type them in - there are no keys for these symbols after all! Do we provide a table to consult? Do we ask them to type them in as “rain” or “snow”? What sort of standard should we use that is both accurate and easy for citizen scientists to transcribe?

Our developer Rob came up with the answer: a drop-down menu which let the users match the handwritten symbol on the page with a list of pre-determined symbols. We created this list from a variety of print sources, including the Instructions to Observers (1878) by George Kingston, the director of the Meteorological Service of Canada and Hints to Meteorological Observers (1908, 6th edition) by Marriott.

This difficulty we faced in trying to figure out a standard to transcribe the weather symbols is not new. The idea of trying to use standard words to describe weather goes back to at least the 18th century. One of the first attempts to coordinate standardized international weather observation was undertaken by the Societas Meteorologica Palatina, in Mannheim. The Mannheim network had stations across Europe and in North America and Greenland. A number of factors including cost and the Napoleonic Wars contributed to its demise in 1795 as international correspondence, even about the weather, came under suspicion of potential espionage!

In the early 19th century, Francis Beaufort and Luke Howard continued the search for a standard way to discuss weather. Howard was the topic of our last blog post about cloud classification systems, and Francis Beaufort was a member of the Royal Navy. As such, he was interested in trying to classify wind strength for ships at sea. The Beaufort Scale describes the force of the wind based on visual cues, such as white caps on waves or the filling of the ships’ sails. Beaufort also devised one or two letter codes for weather such as “rn” for rain. He used “b” for “blue sky”, which is why we sometimes see “b” as an indicator for “clear” - this is a common symbol found in our own ledgers!

This system worked well enough for the English but as time went on countries wanted to exchange weather data and an international standard was needed. Letter codes for weather conditions based on each country’s language were too confusing. A standard that transcended language was needed.

The first international meeting to set standards for land-based meteorological measurements was held in Vienna in September 1872. Question 15 on the docket was “Is it desirable to introduce for Clouds, Hydrometeors, and for other extraordinary phenomena, symbols which shall be independent of local language, and therefore universally intelligible?” According to the minutes there was a long debate on the “advisability and the difficulty of the adoptions of symbols”, in which scientists from Brussels, Christiania, Geneva, Florence, Vienna, London, Padua, and St. Petersburg took part.

Consensus was met though and the following symbols were agreed upon:

weather symbols

And well, the rest is history! You can see these symbols in use when transcribing the weather data from our ledgers. If you are interested in looking at further weather symbols, check out Meteorological Observations for a full list of symbols you might see while transcribing!

For more information check out:

The Invention of Clouds - Richard Hamblyn
The Weather Experiment: The Pioneers who Sought to see the Future - Peter Moore

tags: #weather history

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