If you are on Cloud Nine you are experiencing a feeling of total happiness and content, or euphoria. The American Weather Bureau, between the 1930s and 1950s, divided clouds into classes that numbered from one to nine. The highest, cloud nine, is the cumulonimbus, and reaches up to 40,000ft and looking like white mountains. During the 1950s there was a popular US radio show called Johnny Dollar. It ran an episode during which the hero was often knocked unconscious and then transported to “cloud nine” where he was revived and lived to be a hero again in other episodes. It was through this that “cloud nine” passed into the English language as a popular phrase for the peak of existence.