I suspect the author of this site is Jewish and may believe in Biblical Flat Earth
Based on what I read, I can't imagine him not believing.
Here is the link where he defines "Heaven(s)" or Shamayim
He gives historical thought of how and why Bible translators have reduced the meaning of the firmament to "sky" or "atmosphere".
He also shows that Scripture is clear that Shamayim and raqia (heavens and the dome) are one and the same.
http://hebrewmeanings.blogspot.com/2016 ... m.html?m=1
This link below is a very detailed understanding of the "Firmament"
http://apikoris.blogspot.com/2015/11/the-firmament.html
A Great Resource for Hebrew Translation
Moderators: Paul Zietsman, DaveyT