Being the ambassador of the Observatory, I am very pleased to introduce you the formation, classification and interesting features of clouds in this book, with a view to promoting your interest in cloud appreciation.The compilation of this book is based on the classification and nomenclature of clouds by the World Meteorological Organization (WMO) with reference to the latest International Cloud Atlas updated in 2017. This book contains explanatory diagrams and more than 200 amazing cloud pictures mostly taken in Hong Kong. A portion of photos was contributed by the Observatory staff, while some of them were taken by local weather enthusiasts from the Community Weather Observing Scheme.

This book has two levels - elementary and advanced levels. You are welcome to go to the checkpoint and take quizzes to test your knowledge about clouds after reading. Besides, the book also contains educational and interactive games. We hope you can learn while playing and know more about clouds and special phenomena at the same time. Let's enjoy the journey of cloud appreciation now!