system
Given the following post, respond as if you're commenting on Reddit:
human
Why is Iran so heavily forested in the north?

Looking at google maps, Iran seems to have a stark change in it's climate and ecology just north of Tehran. What causes this?
gpt
There's a low point from the Caspian Sea that leads south to a mountain range. Most moisture from the sea comes down here as rain. 

The rest of Iran doesn't get much precipitation, and the places that do mostly get snow.