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I wandered lonely as a cloud,
That floats on high o’er vales
and hills,
When all at once I saw a crowd,
A host of golden daffodils;
William Wordsworth was captivated
by them; so too were Turner and Constable who spent many years
painting them.
Clouds have always fascinated
mankind but until fairly recently they were just ‘essences’
floating in the sky.
This year marks the 200th anniversary
of the first attempt to describe all the clouds we see in
the sky And it is a system that we still use today.
Luke Howard was an English
chemist who also had a deep fascination with the weather.
He recognised that there were
four main types of cloud.
Lumpy clouds with flat bases
and cauliflower-shaped tops - he called cumulus from the Latin
for ‘heaped’.
Layered clouds - he called
these stratus.
Wispy, curly clouds - he called
these cirrus.
And, of course - being an
Englishman - rain-bearing clouds - he called nimbus.
These definitions appeared
in his Essay on the Modification of Clouds published in 1802.
Cloud occurs between the surface
and 6,500 feet; medium cloud lies between 6,500 and about
16,500 feet.
High cloud lies above 16,500
feet.
That is four clouds and three
layers.
4x3 = 12.
That’s 12 main cloud types.
We have expanded on Howard’s
list and there are now 27 types of cloud plus 14 species and
nine varieties.
This allows us to describe
the clouds very precisely - cumulus congestus, stratocumulus
stratiformis; altostratus translucidus. Do all these obscure
Latin names really matter?
The answer is yes!
Each cloud is an indicator
of different things happening in our atmosphere.
Whether the air is moist,
its rising, descending, unstable or turbulent.
Each one gives us a clue as
to what the weather has in store.
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