'Those clouds aren't natural - they're man-made,' said the taxi-driver, glancing towards the horizon, 'they're all doing it, we're doing it, and the Russians, and the Americans'. For the whole of the ten minute taxi ride I listened to his tirade against cloud engineering. At the end of the journey he gave me his card and wrote a link to a website on the back.
At the time he seemed to be at the cranky end of science, akin to the observers of UFOs, but I remembered that one-sided conversation recently. I've been reading the Richard Hamblyn's book Clouds. The last chapter of the book is entitled 'Future Clouds' and uncovers a long catalogue of cloud engineering. This includes American military aircraft covertly seeding clouds in the hope of causing flash floods along the Ho Chi Min Trail during the Vietnam war, and China seeding clouds in the run-up to the 2008 Beijing Olympics to keep the Olympic Stadium rain-free (it was). In 1977 weather modification for military purposes was banned by an international convention of 40 countries, but cloud seeding is still being used, for example, for crop irrigation and to induce early snow in ski resorts.
More (worryingly) uncertain is the effect on climate change of anthropogenic clouds - created by industry, shipping and aircraft (that solitary contrail scrawled across a blue sky is only the tip of the anthropogenic cloud).
I can't claim to understand all the science in Hamblyn's book but I was impressed by his knowledge of clouds in art, music and literature. He prefaces his introduction with words from Wordsworth's Prelude (Book 1):
'I look about and should the guide I choose
Be nothing better than a wandering cloud,
I cannot miss my way.'
(It makes a change from the famous first line of 'Daffodils')
On a clear day I can see Snowdon from my kitchen window and love Wordsworth's description of emerging onto the summit above the clouds at or just before dawn:
'... at my feet
Rested a silent sea of heavy mist.
A hundred hills their dusky backs upheaved
All over this still ocean,' (Prelude Book 10)
Hamblyn quotes Gerard Manley Hopkins' letter (to the journal Nature) beginning, 'The sky was striped with cirrus clouds like the swaths of a hayfield.' There are several cloud quotations from 20th century poets. Philip Larkin's 'high-builded cloud/Moving at summer's pace' ('Cut Grass') is an example of cumulus cloud. Luke Howard, the man who in 1802 classified clouds under the names we still use today (cirrus, cumulus, strata) has inspired several poets, including Carol Ann Duffy ('Luke Howard: Namer of Clouds'), Billy Collins ('Student of Clouds') and Lavinia Greenlaw ('What We Can See Of The Sky Has Fallen: Luke Howard 1772 - 1864').
I was amazed to read about artificial clouds created by artists for art installations, including Antony Gormley's 'Blind Light'. Timothy Donnelly's futuristic (or is it?) poem sequence The Cloud Corporation describes how
'Fans conveying clouds through aluminium ducts
can be heard from up to a mile away, depending on
air temperature, humidity, the absence or presence
of any competing sound'
and goes on to ponder why manufactured clouds produce more of a response than 'clouds occurring in nature'.
The appeal of clouds to poets is aptly stated by Alexandra Harris (Weatherland): 'Like a much redrafted poem there is no single authoritative version of a cloud. The cloud-form is constantly revised and never finished' (see 'Is it nearly ready?' my blog of 28 May 2015).
Richard Hamblyn's Clouds: Nature and Culture (2017) is published in a lavishly illustrated paperback by Reakton Books.
* As for being on Cloud Nine - it comes from the Hon. Ralph Abercromby's 1896 cloud ranking. It's the ninth (highest) cloud, the cumulo-nimbus.