Who says it can\'t snow or rain?
It rains when it rains on the surface of the planet. How? Water filters down and eventually drops down from the top of the cave.
As well, heat rises up and cold air drops down. Some of the lower levels may have ice because the AIR is -0*C. (water freezes in mid-air) And as well, who says that the
ground isn\'t below 0*C? Water hitting a frozen surface will freeze, too.
Rain in the hot and temperate air temperature levels will probably not freeze - but it might freeze on the levels where the cooler air is denser. and rain may also freeze when it hits the ground, forming ice.
As well, magic may always play a part in it. Tropical/Jungle/Coniferous forrests arn\'t entirely impossible, either. The way i see the levels ecosystems going is:
From highest level to below waterlevel:
Wastelands (No life whatsoever. Not even a single rodent)
Deserts
Savana
Jungle / Tropical }Main habitat for many species
Coniferous Forrests }Main habitat for many species
Forrests / Grasslands }Main habitat for many species
Cold Grasslands
Snowy
Glacial
Water level (Warm)
Water level (Moderate)
Water level (Cold)
Water level (Ice - Cant really go any deeper though some water can continue through small cracks)
And remember that there WOULD be other lakes/bodies of water on each level, though for the upper three that is very unlikely. As well, enviroments are not \"This level is grassland, and only grassland!\" - there is some play inbetween levels.
And, my reasoning for this setup is that the upper levels receive the greatest average amount of types of radiation comming from the crystal - thus a barren wasteland since nearly nothing can handle that much radiation. The lower levels receive the least average amount of radiation from the crystal and thus have less heat transfer and because of that are very, VERY, cold.
[Besides - How fun do you think Planeshift would be if it were
all forrests and grasslands?

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