Page "Geography of Cape Verde" Paragraph 60

Northeastern slopes of high mountains often receive a lot of rain and Southwest slopes not.

This is because they are Umbria areas, situated in the north hillsides or slopes of the mountainous areas, oriented behind the sun in the northern hemisphere, in the shadyside orographic.

So the amount of solar radiation that it receive is much lower than it would if it had without the Island's relief which intercepts much of the sun.

In terms of botanical ecology, these umbria areas are identified as being cool and moist.