It was written by Roger Waters and performed by David Gilmour on vocals and guitar and Rick Wright on organ.
The song has a hallucinogenic, pastoral quality, with prominent organ and bird sound effects, like those later that year featured on the Ummagumma track "Grantchester Meadows".
The Hammond and Farfisa organ coda is similar to that found on the "Celestial Voices" section of "A Saucerful of Secrets".
The opening birdsong is from a 1961 recording entitled "Dawn Chorus" and the single bird featured over the organ part is a nightingale also from 1961.
"Cirrus Minor" was covered by the French artist Étienne Daho on his 2007 album, Be My Guest Tonight.