The usual Old English word for cloud was weolcan. In Middle English, skie also originally meant cloud. The four fundamental types of cloud classification (cirrus, cumulus, stratus, nimbus) were proposed by British amateur meteorologist Luke Howard (1772-1864) in 1802. Figuratively, as something that casts a shadow, from early 15c.; hence under a cloud (c.1500).
Thanks for the A2A. Okay, the most famous song in the world is no doubt 'Happy Birthday', followed by various Christmas carols (since the majority of human population is Christian indeed and since Santa is a really famous guy), folk songs, army marches and national anthems.
Aquarius/Let the Sunshine In - History. 1  This song was one of the most popular songs of 1969 worldwide, and in the United States it reached the number one position on both the Billboard Hot 100 (for six weeks in April and May) and the Billboard Adult Contemporaries Chart.