How can I explain rainforests in a world with little, localized rain?

On the world I am building (Let's call it Bob for simplicity's sake), the days last 9 years. As a result of this, the living beings on Bob must migrate across the planet to avoid the encroaching night. Now, obviously if Bob had continents like Earth, this would be impossible for animals (like the ones that would evolve into sapient beings.). So to combat this, Bob lacks oceans, he instead has large lakes (like the Caspian Sea) scattered every couple thousand kilometers.

Now, without oceans, the weather becomes a bit messed up, specifically the precipitation cycle. Only areas within a few hundred miles (at best) of a lake would get rain, and rarely at that. So, how do I permit rain forests to appear on Bob?

On a world, were rain is rare and not widespread, how can rain dependent biomes like rainforests develop?

posted almost 7 years ago

Uncle Tres‭

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