Why did Moshe see fit to raise his hands heavenwards specifically by Makas Barad?
Ramban: Refer to 9:29:1:2.
Oznayim la'Torah: It is a hint that Moshe stopped the hail from falling in mid-air. 1
What does the Torah mean when it writes "u'Matar Lo nitach Artzah"?
Rashi #2 (citing Menachem ben S'ruk) and Rashbam: It did not pour on to the ground.
Rashi #3 (in Yechezkel,13:11): When the Pasuk there speaks abou "Avnei Elgavish, it is referring to the hailstones that Moshe stopped in midair
According to the Ta'amim, Targumim and Rashi, the Pasuk means that the hail stopped, and the rain did not reach the ground.
It stopped in mid-air. Rabeinu Bachye (citing Midrash Tanchuma) relates that they would later fall on the Cana'anim in the time of Yehoshua (as recorded in Yehoshua 10:11), whereas, according to the Gemara in Berachos (54b, it was Yechezkel who ordered them to fall [See Rashi Yechezkel, 13:11]). Hadar Zekenim - it will fall in the days of Gog and Magog.