Name that cloud
By Storm Dunlop
World Meteorology Day marks a highly successful collaboration under the World Meteorological Organization, involving every country, large or small, rich or poor. Weather affects every single person (every living being) on the planet, but why do people feel meteorology is not for them? Why do they even find it so difficult to identify different types of cloud? Or at least they claim that it is difficult. The average person, it would seem, looks at the sky and simply thinks ‘clouds’. (Just as they look at the night sky and think nothing more than ‘stars’).
Is it because they think there are so many — too many to remember? Yet there are just ten major types, and most people can recognize ten different makes of cars, ten different dogs, or ten different flowers. Can’t they? Perhaps not. Some people do have poor visual discrimination: my father for one. Show him a piece of oak and a piece of pine, and he would not know, by sight, which was which. To him, it was ‘wood’. Then some people apparently suffer from a difficulty in transferring what they see in a photograph or illustration to the real world. I can think of an experienced amateur astronomer who cannot match a photograph of the night sky that he has taken to the actual constellations above his head.
There is the old philosophical argument about whether one can even think about an object or concept, without having a name for it in one’s head. Surely, however, one can have a mental image of a physical object, such as (say) a sea-cucumber, without knowing that it is called a sea-cucumber or even a holothurian? As an author, my brain functions with words, not images. I suppose that conversely, perhaps if people are unable to hold a mental image of a cumulonimbus cloud, they cannot assimilate its name.
Or is it the words themselves that put them off? Luke Howard in his seminal work On the Modification of Clouds (1802) introduced Latin terms, following the tradition set by Linnaeus. Scientifically, that was (and remains) perfectly sensible. But is that the root of the problem? It seems to be a modern myth that all Latin is ‘difficult’, and the hoi polloi — sorry, that’s Greek! — (‘the masses’) avoid it in all forms. Perhaps this fear arises because it is no longer taught widely, no longer a requirement for university entrance, and no longer (for Catholics) heard in the Latin mass. But it is at the root of so many languages and so many scientific terms that this phobia is deeply regrettable.
The words for clouds themselves are hardly difficult: terms such as nimbostratus are hardly pronounceable mouthfuls. Do people worry that, like Silas Wegg in Dickens’ Our Mutual Friend, who turned the Greek historian Polybius into the Roman virgin Polly Beeious, they will get even these wrong? I suppose I am fortunate, because I did learn Latin at school, and I speak and read various languages, so words, from whatever source, don’t frighten me. And I like to get any pronunciation right. I also have to admit that if I know a word, I tend to use it. That may be why people look at me a bit oddly when I use words such as chlorofluorocarbon or the name of that Icelandic volcano — strictly speaking, the glacier — Eyjafjallajökull that caused all that trouble.
Of course, it is not just clouds that suffer from a general ignorance of meteorology. Witness the amazement that seems to arise if someone spots a funnel cloud, a display of nacreous clouds, or even something as common and innocuous as a solar halo. And the utter media frenzy if a ‘twister’ (the media’s word for a waterspout, landspout, true tornado or any other form of whirl) does actually cause some damage. Given that the source of most information about the weather for the general public comes from TV weather presenters, perhaps they could be encouraged to slip in, instead of their usual rather feeble jokes, something like ‘The front will be followed by scattered cumulonimbus, or shower, clouds.’
So we must applaud attempts to get the general public more interested in the weather and clouds in particular. Efforts such as the Cloud Appreciation Society, and the WeatherClub set up for the general public by the Royal Meteorological Society, and its publication theWeather are to be welcomed.
Knowledge of the natural world (including clouds) should be part of everyone’s general understanding. Clouds should be viewed as an easy introduction to a vast range of fascinating phenomena.
So here is a list of those ten clouds, arranged conventionally in three height levels with the highest first in the list. It is, however, easiest to learn them from the bottom up. (Start with cumulus, the ‘cotton-wool’ fluffy, ‘fair-weather’ clouds.)
Cirrus: Thin wisps of ice-crystal cloud at high altitudes
Cirrostratus: A high-altitude, thin layer of ice-crystal cloud, formed from the spreading out of cirrus. Often shows some fibrous structure.
Cirrocumulus: A high-altitude layer of tiny heaps of ice-crystal cloud with no shading and clear gaps between the cloudlets.
Altostratus: A middle-altitude layer of essentially featureless, white or grey cloud.
Altocumulus: A middle altitude layer of moderate-sized heaps of cloud, with distinct shading and clear gaps between the cloudlets.
Nimbostratus: A dense layer of cloud at middle levels, often extending down close to the surface. Often with a ragged base, and always producing prolonged rain.
Stratocumulus: A widespread layer of heaps or rolls of cloud at a low level, with distinct gaps and heavy shading.
Stratus: An essentially featureless, grey layer of cloud at low level. At ground level, it is mist or fog.
Cumulus: The most familiar cloud. Rounded heaps of white cloud at low levels, generally an indication of currently fine weather.
Cumulonimbus: The giant among clouds, that may tower through all three levels, sometimes with a flattened top (an ‘anvil’). The shower cloud with dark, ragged base and heavy, localized rain, hail, or other severe weather.
So celebrate World Meteorological Day! Live Long, Learn your Clouds, and Prosper!
Storm Dunlop, an experienced writer on meteorology and astronomy, is the author of A Dictionary of Weather. He is a Fellow of both the Royal Astronomical Society and the Royal Meteorological Society, and the photographic editor of the journal, Weather. He is also past president of the British Astronomical Association and has given many lectures and talks on all aspects of meteorology and astronomy. You can find out more about clouds in A Dictionary of Weather. You can also access a fully searchable, online version of the dictionary on Oxford Reference Online (check with your library to see if they subscribe).