The WMO (CIMO) International Cloud Atlas — Revision for the 21st Century

The WMO International Cloud Atlas has a long and rich history. Its first edition was published in 1939, though its origins date back to the 1800s. Subsequent editions were published in 1956 and 1975, with the most recent edition of Volume II, containing more than 200 photographic images of clouds and meteors, published in 1987. Although it is a very popular collection of information on clouds, the fundamental purpose of the ICA is to ensure that cloud observers around the world apply uniform standards in coding and reporting cloud observations. Since 1987, much in the world has changed. In particular, we can now use the power of the internet, and take advantage of the many modern high quality images to make the ICA more flexible and complete. The WMO is now in the process of revising and updating the ICA with many enhancements. The new ICA will be fully web-based, with new images, more complete descriptions, time lapse or video imagery, and a new glossary. Of particular importance are some changes to the cloud classification scheme, and addition of imagery to show seasonal and climatic variation in cloud appearance. This presentation will summarize the plans and current status of this revision.