A new International Cloud Atlas (ICA) edition was launched on World Meteorological Day (23 March) 2017. For the first time the ICA is now in electronic format as an open-access website available at: http://www.wmocloudatlas.org/.
The ICA has many purposes, but fundamental is its role as the source of advice and mandatory instructions for cloud observing and reporting as part of the World Meteorological Organization (WMO) Integrated Global Observing System (WIGOS).
The most significant changes for observers are additions to the classification scheme, a greatly expanded set of photographic examples and explanations, and the ability to compare pairs of images side-by-side.
Further details are available from the latest WIGOS Newsletter.