Water, earth and air

[Jorge_Stolfi]

In Sacrobosco's De Sphaera manuscripts the spheres were named but drawn without symbols but in some later printed editions the symbols are clearly drawn, for example in the You are not allowed to view links. Register or Login to view..

So this infurled style of band is frequently used to represent a division between realms (usually heaven and earth), but it can also represent “air”.

Indeed, in that Regiomontanus printed book (1488), page 19, there is an "Aristotelian" diagram of the cosmos, with Earth at the center (represented as an original complicated version of the T-O map) surrounded by the spheres of  Water, Air, Fire, Moon, Mercury, Venus, Sun, Mars, Jupiter, Saturn, and the Stars.  (There is an outer band with the signs of the Zodiac, but it does not seem to imply an additional sphere.)

And the sphere of "Air" is indeed drawn as a wolkenband.

All the best, --stolfi