The Cloud Appreciation Society was founded by Gavin Pretor-Pinney in 2004, to 'fight blue-sky thinking', with the motto: 'Look up, marvel at the ephemeral beauty, and live life with your head in the clouds': Sound advice if ever I heard it. The Cloudspotter's Guide is its first official publication, and the author's first book.

Pretor-Pinney also designed the Guide, typeset it and put together the diagrams, and in every case he has done a beautiful job. This volume is gorgeously produced, with a delightful, atmospheric woodcut opening each chapter, plentiful photography throughout (mainly contributed by members of the Society) and the old iconic cloud symbol from the BBC's weather forecasts serving as a vignette between each section. All in all, the design gives the book a dreamy, flighty air, in keeping with both the subject matter and the style of the prose.

The writing is fluid and un-self-consciously eloquent, rambling without ever getting tedious, educational without ever getting lecturey. The author skips amiably from topic to topic, interweaving personal and historical anecdotes, scientific observations and poetic ruminations on the beauty and vitality of the skies.

Each of the major classes of cloud has a chapter dedicated to it, always going into some depth about what characterises the clouds in question and talking a little about the meteorology of it, but often spending more time talking about other things - clouds in history and art, say, or various phenomena that come along with the clouds themselves (most of the Cirrostratus chapter is devoted to discussing ice haloes, for example; much of Nimbostratus is about rain from all sorts of different clouds).

The beginning of each of these chapters features a summary table for the clouds that are its nominal subject, giving a few illustrative photos, telling you where they form, in what species and varieties they appear, how to distinguish them from any superficially similar clouds, and so on.

The scientific details are substantial enough to satisfy the amateur meteorologist in me, but never so technical as to bog down the flow of the writing; where the author has had to simplify to make it comprehensible to the general reader, he is not afraid to say so, and the insatiably curious can always follow his pointers to more in-depth work.

After the ten chapters for the main cloud groups, the last section of the book ('not forgetting...') goes onto things which couldn't quite be fitted in elsewhere. First, there is a chapter on The Other Clouds - accessory clouds such as the pileus ('like a cloud haircut') and pannus ('dark shreds of condensation, which form like ghostly apparitions in the saturated air of rainfall') which only appear alongside other clouds; supplementary features such as the incus (anvil) that often extends from the top of a Cumulonimbus cloud, or the breast-like mamma clouds that occasionally blob from the bottom of that; and the high, high clouds that form way above more common clouds, up in the mesosphere or the stratosphere - nacreous and noctilucent clouds respectively.

Chapter Twelve's subject is contrails, the trails of condensation that form behind high-altitude aeroplanes. These streaks may provide an interesting glimpse into the process of cloud development, but they are also strongly implicated in climate change; it is largely thanks to them that the contribution of aeroplanes to the greenhouse effect is almost three times as large as it would be if CO2 was the only thing we needed to worry about. Much of the chapter is spent exploring the threat of global warming as it relates to aeroplane exhaust, with a substantial portion also given over to the history and science of cloud seeding - a technology which can be surprisingly effective in inducing rainfall (albeit only when the conditions are right), and which gets discussed oddly rarely considering the power of it.

In the final chapter, the author goes into journalist mode to recount in detail his mission to visit the Morning Glory, a spectacular and near-unique cloud formation in northern Australia, where rolls of cloud can be seen stretching from horizon to horizon as they make their way over the outback. Glider pilots come from all over the world to surf on its extraordinary, visibly roiling updrafts, and witness one of the world's most awesome clouds. Despite the stylistic departure, the story provides a surprisingly elegant close to the book, as the author soars alongside some of this planet's most devoted cloud-lovers.

This writeup also appears in my blog at http://oolong.co.uk/oo/?p=9.
The Cloud Appreciation Society's web site is at http://www.cloudappreciationsociety.org/.
Ice haloes are covered in glorious detail at http://www.atoptics.co.uk/halosim.htm.