Why - they are - above - the firmament - of course!
I call it "that place above the firmament"...
hahahahaha
JK
The way I currently see it:
Above the firmament is a dome which contains the atmosphere that is below it. It sits upon the earth hundreds or thousands of miles beyond "the circle of the earth" (Isaiah 40:22) - which is the "ice ring" that contains the oceans.
Either the dome itself is made of water or the dome is made of some impervious transparent material with water above it.
The sky is blue because of the water above the firmament.
The dome makes possible "sun dogs" and rainbows.
The third heaven is beyond the dome.
The second heaven is the upper part of the firmament under the dome - where the sun, moon, and stars are.
The first heaven is the lower part of the firmament above the earth - where the birds fly. (and where the clouds are)