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A Problem with Small Oceans?


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I was just reading GTD, page 84, reading the description of Frieden, I come across mention that the currently settlers are in a city on the shores of the only ocean of any size.

I look up at the UWP and see the Hydrographics are 2.

At this point, a number of things begin clicking into place.

The UWP Size is 7, or almost Earth-size. Yes, only 20% of the coverage (unknown depth and volume) is liquid.

The UWP Atmosphere is 9, Dense Tainted.

Is a "dense" atmosphere capable of retaining a greater degree of humidity than a standard atmosphere?

Since a body of water as large as the Mediterranean completely evaporated in the past when cut off from the oceans, even though major rivers drained into it and it received rainfall (and the rest of the world still has its giant oceans), then wouldn't a small ocean covering only 20% of the surface (with an Atmosphere that might be capable of carrying a far heavier load of water than on Earth) evaporate? After all, any evaporate water will wind up diffusing through the Atmosphere, with any precipitation coming down anywhere, including drainage areas not returning to the ocean.

I don't know, I just get the impression that such an ocean's water would wind up getting dispersed across the world. Or, better yet, if dispersion is acting like this, how could a small ocean form in the first place?

Ok, now time to shoot me down . . .
Well, if I've done my maths right, a single ocean covering 20% of a size 7 planet has a surface area of about 78.8 million square km. Which is about the same area as the entire Atlantic ocean (from pole to pole), which covers about 15% of the earth's surface - so it's really quite large. For comparison, the Mediterranean sea covers only 2.5 million square km, or about 0.5% of the total surface area of Earth.

As to how shallow or deep it is... that largely depends on the tectonic setting. I could picture such an ocean having a mid-ocean ridge where it's growing running down its middle and subduction zones (and volcanoes) at the edges. Or it could be shrinking if you have rifts in the continental crust and no mid-ocean ridge. But either way, the sea itself could certainly be as deep as the Atlantic is on Earth.

As to "how much humidity a dense atmosphere can hold"... I dunno. I don't think it works like that. I'm sure the earth's atmosphere could hold all the earth's oceans in vapour form if the temperature rose high enough to evaporate them (obviously, it'd thicken quite a bit in the process too). But large bodies of water don't evaporate unless all inflow is cut off (the mediterranean, BTW, has not completely evaporated AFAIK. The Dead Sea, however, is evaporating today. Have a look here for some useful info on the Med.

So I think that a single body of water covering more than a couple of % of the surface area of a largeish planet shouldn't have any trouble surviving, so long as rivers flow into it and there's a decent water cycle going.
Originally posted by Malenfant:
(the mediterranean, BTW, has not completely evaporated AFAIK.
Decades ago, scientists went around the Med in the Glomar Challenger ( Wikipedia.org Entry, NationMaster.com Entry, both sites back each other up) trying to take core samples. But it's drill kept impacting on a hard surface for which there was no explanation at the time. The stuff they got up from the bottom was interesting indeed, there are layers of hardened sedimentary salts alternating with marine deposition sedimentation. It's a major theory that the Med, having been cut off from the Atlantic in the past, largely dried up (whether it was 100% dry or not at any one time is debateable, of course).
The amount of water vapor which can be held in the atmosphere is independent of pressure -- it's a function of temperature.