What is "Af Bri"?
Rashi: It is the angel appointed over the clouds.
Tosfos (Nidah 16b DH Mal'ach): It is the angel appointed over rain 1 . It acts only with Hashem's permission, for rain is one of the three keys in Hashem's hand that was not handed over to a Shali'ach.
Ibn Ezra: There is a time [when the air is clear]. Even then... (refer to 37:11:2:2).
Ibn Ezra: Some say that the Beis in Bri is a prefix. Ri is like Revayah (saturation). This is difficult.
Also the start of Tefilas Geshem (for those who say it in Chazaras ha'Shatz) calls it "Sar ha'Matar.' (PF)
What is the meaning of "Yatri'ach Av Yafitz Anan Oro"?
Rashi: It scatters Hashem's rain cloud.
Ibn Ezra: Yafitz is spreading, like "Yafutzu Mainosecha Chutzah." The cloud spreads its light - rain falls and the sun is seen.
Malbim: White snow and hail is a toil and burden for the cloud; it cannot bear it more. The cloud scatters its Ohr 1 below.
Above (3), Malbim explained that Ohr is lightning. Here, from context, it seems that Ohr is the snow and hail; the cloud cannot bear them, and drops them. (PF)
