What is "Shmei ha'Shamayim"?
Radak #1: Some say that they are Elyonei (the highest 1 in) Shamayim. This is like "Melech Melachim" (Yechezkel 26:7).
Radak #2: This is what is below Shamayim - a ball of fire near the moon. Ha'Shamayim is the air called Shamayim - "Al Pnei Raki'a ha'Shamayim" (Bereishis 1:20).
Malbim: From the rain clouds and above is called Shamayim - "va'Yikra Elokim la'Raki'a Shamayim" (Bereishis 1:8). Above them, until the Galgal of the moon, is called Shmei ha'Shamayim. There is the upper water suspended via the King's word, like I explained in Ma'ase Bereishis.
Radak: According to this, it is not physical. 'Elyonei' is the highest level; it does not refer to place. It is the world of Nefashos.
What is "Mayim me'Al ha'Shamayim"?
Radak #1: Also this is not physical. It is a form from which forms come. "[u'Vein] ha'Mayim Asher me'Al la'Raki'a" (Bereishis 1:7) refers to this.
Radak #2: This is the ball of ice; it is between the ball of fire and the air close to us. It is the extent of where the clouds reach to 1 .
Malbim: Refer to 148:4:1:3.
Radak: Investigators disagree. They say that there is only air between us and the Galgal of the moon, and natural fire. If so, "Mayim" is the form of water. It is the extent of where the clouds reach to in the air. There, they draw water from the air, and it falls naturally to the ground. There is no other body there, only air, but it is qualitatively different.
