What does "b'Aneni Anan Al ha'Aretz" mean? What is this Pasuk coming to add?
Rashi: "Anan" has connotations of darkness and destruction. The Pasuk means that when HaSh-m has thoughts of bringing upon the world darkness and destruction, He will see the rainbow and desist.
Rashi writes: "When I gather clouds upon the earth - when I consider bringing darkness and destruction upon the earth." Why doesn't Rashi suffice with the literal meaning of the words?
Gur Aryeh: It often happens that there are clouds but no rainbow; therefore, our verse must allude to "darkness and destruction."
Why does the Pasuk never mention the rainbow without mentioning the clouds?
Seforno: Because it is never seen without a thick cloud, following a clear period and rain.
Targum Yonasan and Ramban 1 : The clouds mentioned here refer to the Clouds of Glory, i.e. Midas ha'Din. In other words, whenever the Midas ha'Din proclaims the world guilty, the rainbow will appear. He also adds that the rainbow will only appear before the sun sets, It cannot appear by night, when there is no sun.
The Ramban adds metaphorically, that the sins of the people prevent HaSh-m's Face from shining on them.
רש"י: כשתעלה במחשבה וכו': למה לא פירש כפשוטו?
גור אריה: פעמים רבות יש ענן ואין קשת, ועל כרחך שמדובר כאן על מחשבת פורענות.