Gavin Pretor-Pinney is founder of the Cloud Appreciation Society, which has more than 60,000 members in 120 countries. He is the author of the internationally bestselling Cloudspotter's Guide and Cloud Collector's Handbook. His third book, The Wavewatcher's Companion, won the prestigious Royal Society Winton Prize for Science Books. Gavin is a TED Global speaker with over 1.2 million views. He has presented television documentaries for the BBC and Channel 4 and is a Visiting Fellow at the Meteorology Department of Reading University and winner of the Royal Meteorological Society's Michael Hunt award. William Grill is a Bristol-based illustrator whose main interest lies in narrative illustration and publishing. He draws most of his inspiration from the natural world, and enjoys working in coloured pencils and occasionally printmaking processes like lino and lithography. His first book, Shackleton's Journey, won the 2015 Kate Greenaway award and has been translated into over fourteen languages, and his second book, The Wolves of Currumpaw, won the 2016 Bologna Ragazzi Prize for Non-fiction.