The phrase, “to be on cloud nine”, generally means that someone is so elated that they are walking on a cloud. With all the clouds in the sky, why did they choose number nine?
I have heard a number of origins for this popular saying, but the one that makes the most sense to me comes from the pioneering days of meteorology. According to this theory, cloud number nine refers to a cumulonimbus cloud … the towering anvil shaped cloud of violent thunderstorms.
The story goes back to 1802 when an amateur British meteorologist named Luke Howard developed a basic nomenclature for clouds. He gave us names like cumulus, stratus, and cirrus. His system followed the Linnaean ideas already in use with flora and fauna. As the science of meteorology developed, different nations soon created their own weather vocabularies and classification systems. This lack of consistency was creating confusion, especially since weather does not recognize national boundaries. Before we had radar and satellites, the study of weather and early forecasting relied on cloud identification and communications between weather stations. To function properly and advance the science, these communications needed a uniform system of identification and measurement.
In 1896, an International Meteorology Conference was held in Paris to establish a uniform standard of cloud classification. The committee built on Luke Howard’s Latin-based scientific names and set up the convention of grouping clouds according to their altitude. The product of this conference was the The International Cloud Atlas. This reference book used photographs and drawings to identify the ten cloud types agreed upon by the committee. Cumulonimbus was number nine on their list.
A cumulonimbus is the tallest of all cloud types. So, to be on cloud nine is to be on the highest cloud in the sky. In a later edition of the Cloud Atlas, the order of list was re-arranged and cumulonimbus was moved to number ten. The phrase, however, is still with us.
The International Meteorological Committee still exists today in the form of the World Meteorological Organization within the U.N. They continue to publish The International Cloud Atlas.
The Ten Cloud Types
Photo Credit: Cloudloverclub