Water, earth and air

[eggyk]

Even ignoring its probable sourcing from the Oresme diagram, the figure of f69v3 almost certainly depicts the same concept of the cosmos: with "land" and the "waters below" (seas) at the center, surrounded by the stars, separated from the "waters above" by the vault of the "sky".  The wavy line of f68v3 should have been the latter, and therefore should have been a "wolkenband" as in the Oresme diagram -- not a nebuly line.  

But actually it is neither: it has a 3D effect (unlike the "nebuly line" of heraldry) but not the fine frills along the edge (unlike the standard "wolkenband").

I'm a little confused with the different terminology being thrown around here, but these "undulations" patterns do indeed have examples of a non-frilly line being used to depict - I think - a seperation between the earth and other planes of existence (heaven, the sky etc). 

There is an example of this in You are not allowed to view links. Register or Login to view.

Around each personified planet depiction there is a undulation pattern. The ones in this example have no frilly patterns, but do maintain that 3D look. 

The planetary section starts on 41r: You are not allowed to view links. Register or Login to view.

Here is saturn:

   

However, just after the section on 53v (You are not allowed to view links. Register or Login to view.) a frilly undulation-like pattern is used to depict the 10th heaven.

   

So I think it is possible that the pattern does not always require the exact frilly pattern, it just matters that the reader understands that the pattern represents a cosmic boundary of sorts.

Edit: There is also use of frilly wolkenbands for what seem to be actual clouds, immediately after a non frilly pattern used as a boundary, on folios 108-110. So it's clear that the meanings of each style were flexible, at least.