Clouds have been objects of delight and fascination throughout human history, their fleeting magnificence and endless variety having inspired scientists and daydreamers alike. Described by Aristophanes as "the patron goddesses of idle men," clouds and the ever-changing patterns they create have long symbolized the restlessness and unpredictability of nature, and yet they are also the source of life-giving rains. In this book, Richard Hamblyn examines clouds in their cultural, historic, and scientific contexts, exploring their prevalence in our skies as well as in our literature, art, and music. As Hamblyn shows, clouds function not only as a crucial means of circulating water around the globe but also as a finely tuned thermostat regulating the planet's temperature. He discusses the many different kinds of clouds, from high, scattered cirrus clouds to the plump thought-bubbles of cumulus clouds, even exploring man-made clouds and clouds on other planets. He also shows how clouds have featured as meaningful symbols in human culture, whether as ominous portents of coming calamities or as ethereal figures giving shape to the heavens, whether in Wordsworth's poetry or today's tech speak. Comprehensive yet compact, cogent and beautifully illustrated, this is the ultimate guidebook to those shapeshifters of the sky.