Knights & Knaves Alehouse

Aha - I was assuming that everything between that big river delta and the jungled hills was desert. If that area's normal terrain, then it makes perfect sense.

Altitude can make a difference, too. If the desert is a mesa or plateau and both the river delta and the jungle are lower in altitude, that might help account for the clouds dropping their water in such a fashion as to produce the geography proposed.

Just my two bits.

Stonegiant wrote:the prevailing winds come from the southwest. In the "bowl" as I refer to it the terrain is delta/swamp, grasslands, than jungle/forest

The winds from the southwest pass across the delta/swamp, then the grasslands, then across the jungle... the ground gently rising the whole way, thus forcing the air mass higher.

Adiabatic cooling* reduces the water-carrying capacity of the air, and it releases most of its moisture as rain (possibly snow in the highest elevations**), which creates the jungle. Runoff from the jungle waters the grasslands (along with the early rains), then spreads out forming the delta/swamp.


As the air passes across the peaks and begins to decend, it heats. This increases its water-carrying capacity, which allows it to retain all remaining moisture, creating a "rain shadow desert".


The only problem I see is that the areas north-west and south-east of the mountain bowl would likely be grasslands/scrub, not desert, although desert could form inland a ways... it would just not be as close to the coast as that in the "rain shadow".


*the drop in temperature of rising, unsaturated air is about 10 degrees C/1000 meters (5 ½ deg F per 1000 feet) altitude.
If water vapor in the air is condensing, the adiabatic rate is less. The air is only cooling off at a rate of about 5 degrees C/1000 meters (2.7 deg per 1000 feet).
http://daphne.palomar.edu/jthorngren/ad ... cesses.htm

** temperate rain forests, which experience occasional snow, do exist... see the Olympic penninsula in Washington state)

Algolei wrote: (How does the desert region along the Pacific coast of South America work again? I forget, it's been so long since high school geography class. . . . )

The prevailing winds in that part of South America are east>west, thus creating the above-mentioned "rain shadow desert" as the water is dropped on the east side of the Andes range. This is still the case where the desert is a "cold desert", as there is no moisture left in the air after it crosses the Andes.

Alright here is the latest incarnation of the map. Made some changes based on discussions here and also for the sake of the campaign I am designing.

Nice work, Sean.

I like it.

Looks like it would be great photocopied as a player handout, with all kinds of fun to be had exploring beyond the mountains.

A most excellent map.

That's really, really nice Sean! I may have to hit you up for a map . . .

- Wheggi