Gavin Pretor-Pinney on the Joy of Clouds

Cloud afficionado Pretor-Pinney, who not only formed the Cloud Appreciation Society (which has 30,000 members!), but wrote 'The Cloudspotter's Guide' too. Today he'll share his sky-high views with the audience and convince them that clouds are better than clear blue skies and talk people through how to distinguish between various cloud formations.