פירוש על שמות 9:23

ותהלך אש ארצה, the atmosphere which had already been heated descended earthward with the same speed as the hail. [Normally, fire has a tendency to rise into higher levels of the atmosphere. Here, the reverse happened. Ed.]

ויט משה את מטהו על השמים, ”Moses stretched his staff heavenwards.” According to Ibn Ezra, the word שמים here is an alternate for the word “atmosphere.” We also find the expression רקיע השמים as referring to the atmosphere and not to celestial regions.