Question

How can air masses affect the nile river lower africa wouldnt the mountains protect it?

Answer 1

Air masses can also come in from the North, across the Mediterranean.

Answer 2

But would that make it still flood?

Answer 3

Rivers flood from excess water, not air masses. Before the dams were built on the Nile, snow melt from the mountains south of Egypt flowed into the Nile and flooded the river valley.

Answer 4

so the mountains arent close to the river?

Answer 5

The Nile's sources -- the small tributaries that feed into the White Nile -- are in the mountains.