Frozen underdark

[tonyblitz1]

I'm building up a 3.5 converted dark sun campaign.
And I've introduced drow as a nightime scavengers race with cold endurance that retreat underground during the day.
The interconnected network of the Underdark has collapsed leaving the populations separated into small tribes.

I want the Underdark to be a harsh dark and freezing place in contrast to the desolate desert wasteland of Athas' surface.
but I'm having trouble finding resources for building it.
Aside from frostburn, which mostly covers above ground cold environments.

[Thurbane]

Underdark and Drow of the Underdark are the best sources of underdark material.

[Kelb_Panthera]

I'm building up a 3.5 converted dark sun campaign.
And I've introduced drow as a nightime scavengers race with cold endurance that retreat underground during the day.
The interconnected network of the Underdark has collapsed leaving the populations separated into small tribes.

I want the Underdark to be a harsh dark and freezing place in contrast to the desolate desert wasteland of Athas' surface.
but I'm having trouble finding resources for building it.
Aside from frostburn, which mostly covers above ground cold environments.

Do you have Underdark? If you do, combine the weather and ground hazards from Frostburn and the spelunking hazards of Underdark in whatever ways you find interesting. Simple fact is: natural underground environs hover pretty close to the low 50s (11~ish in °C) no matter your latitude or altitude. Glacier crevasses are the closest you get to an exception.

[BowStreetRunner]

You shouldn't have any trouble coming up with a justification for the extreme colds to be prevalent in the underdark, regardless of real world conditions underground. Athas already has established canon stating that sorcery steals its power from the life force of living things. Energy theft of a similar type could explain the cold underground. Maybe something like the Pristine Tower is still around, but in this case sucking the heat out of the very ground to power whatever effect it creates on the surface.

[Palanan]

Originally Posted by Kelb_Panthera
Simple fact is: natural underground environs hover pretty close to the low 50s (11~ish in °C) no matter your latitude or altitude.

A quick Google search brings up Korallgrottan (http://naturescandinavia.se/korallgrottan-about-swedens-longest-cave/), which is at a maximum of 39° F (4° C) in the summertime.

And in Barsukovo Cave (https://www.rbth.com/travel/2015/29/01/siberias_most_beautiful_winter_caves) temperatures can be 0° C depending on the season. This is certainly warmer than the surface temperature in a Siberian winter, but it’s hardly a consistent 50° F year-round. There are other examples easily found, but you get the idea.


Originally Posted by BowStreetRunner
You shouldn't have any trouble coming up with a justification for the extreme colds to be prevalent in the underdark, regardless of real world conditions underground.

Sorcerous energy theft from the earth itself is a cool idea, but there could be more natural explanations as well, which could dovetail with a geological dead zone over a broad area.

.

[Fouredged Sword]

The tendency IRL is for the dirt of sufficient depth (30ish feet down) to be at the surface's average yearly temperature.

The surface dirt provides a insulating effect that moderates the change in temperature of the dirt beneath it. It warms and cools more slowly the deeper you go until it stabalizes at a point where the yearly hot/cold cycle and day/night cycles no longer effect it.

Find the first layer of dirt that stays at a constant temp all year round (it varries due to soil comp) and you have found that area's average yearly temperature.

Go deeper and you start being warmed back up by tectonic forces and eventually magma.

Local features like volcanos or glaciers can throw this off.