Why are the south, the west and the north of the Caspian sea lush but its east completely dry?

Question

About the Caspian sea area today:

• The south is very lush with the subtropical forests of the Iranian provinces of Gilan, Mazandaran and Golestan (although less "tropical" in Golestan)
• The west tends to be lush with subtropical (?) thicket and also forests around Baku and lots of thicket at least up to Derbent
• The north is pretty much part of the Euroasian Steppe but might not have been until the rise of the Khazar empire or earlier --- Scythian empire in the region which might have caused significant deforestation although still has some rich thicket/grove areas left today

And yet, the eastern coast of the Caspian sea seemed to me from almost any image as a dry "wasteland", with almost no thicket and certainly nothing I would name "a forest".

Why are the south, the west and the north of the Caspian sea lush but its east completely dry?

Answer 1

The mountains.

The south has a steep relief, as well as the west. That means that there is much precipitation. The clouds throw every drop on these mountains, so almost nothing is left. The east is pretty low, so the remaining clouds (not much left) just fly over. In fact, deserts are generally not steep and they are usually behind the mountains. That is right what happens here. On the north, the effects of the west are still felt, so it isn't so dry, but it is pretty low, too. Also, I wouldn't say that it's lush : )