Three-section orbs

[nablator]

I wonder, if three distinct bands surrounding the Earth are named in the text.

In the text maybe not. Not on the same page anyway in this printed edition: You are not allowed to view links. Register or Login to view.

But the spheres are all named in many manuscripts. Here the 9th sphere is the primum mobile, equating it to the crystalline sphere:
   
You are not allowed to view links. Register or Login to view., fol. 17r.

C[a]elum Empyreum est locus beatorum et est sp[ha]era immobile.
Sp[ha]era nona vel primum mobile secundum theologos dicitur c[a]elum cristallinum vel igneum secundum antiquos ut dicit Aristoteles...

The text does mention the "spheres of the elements":
   

Many printed editions (this one is dated 1509) just have a single "sphere of the elements" in the center:
   

So, the wavy thing under the fire ring here is the air element?

Yes!