Like most things in the allsky, this heavencloud is made mainly of waterstuff.
Waterstuff, also known as Lightmote, is the first of the shafts, and smallest of the shaftmotes. Its token is (H). A greaterhood of the inweight of the heavens is waterstuff. The name comes from water, a bindishaft of waterstuff and sourstuff, wherein is found most of the waterstuff on Earth.
The meanest samestead of waterstuff is 1H, with but one ekemote and no greymotes. The other samestead, 2H, has one of each. Being twice as heavy, it behaves with enough otherness to have its own token, D. The third samestead, 3H or T, has two greymotes and is light. The first samestuff, without the greymote, is found six thousand times more often than the other, and the third kind can only be made by men.
Waterstuff was wrought in the the big bang, and in the bellies of stars it melts together into sunstuff. This is what gives the Sun and stars their heat and light. Stars togethermelt the mean ilk of waterstuff, but men can only do so with the more geason samesteads, with one or two greymotes alongside the ekemote.
When unmingled with other shafts, waterstuff is found as a two-uncleft mist. This is so much lighter than the liftshell about it that waterstuff was once brooked as a lifting mist for liftships. But waterstuff is firefeeding, and after the wreck of the liftship Hindenburg in 1937 it was given up, with the idlewind sunstuff taking its stead.
Waterstuff cannot be found in the Earth's liftshell owing to the sourstuff, with which it will burn to make water. Rather, to get it, men must cleave the water bulkbits with a levenflow and gather the waterstuff ere it rises into the high layers of the liftshell, where it will burn or be shed into the heavens for its lightness.