Why do phospholipids form a double layer, and how does this affect the permeability of the cell membrane?

They form a double layer to make sure nothing harmful goes in the cell. It affects the permeability of the cell membrane by making sure nothing big and polar passes the boundaries of the cell.

Nimbostratus is the correct answer.
explanation: nimbostratus clouds are the type of clouds that are mostly likely present on gray, rainy day. these clouds produce continuous rain, snow and there is no thundering or lightening either.