David Meadows
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Registered: 09-2003
Posts: 165
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Re: Planetary parameters
Millions of years ago, the Earth had a global ocean with one big polar continent, and that continent wasn't locked into permanent winter.
There's an interesting paper by Williams, Kasting and Caldeira, "Habitable Planets with High Obliquities" (sorry, I don't have an on-line reference for it) which shows how the habitability of a south polar supercontinent changes with the angle of planetary tilt. At 23 degrees (such as the Earth currently has) a southern supercontinent would have an ice-free season. At higher angles, the amount of ice-free land decreases, until at 90 degrees of rotation 90% of the land is permanently icebound, making the planet effectively uninhabitable.
Unfortunately, the picture isn't as simple as their model's assumptions -- there are lots of other factors which affect which affect climate, not just the angle of tilt.
But if you want a large polar frozen area, you could consider making the planet's axial tilt greater than the Earth's. But then you might just be giving yourself the bigger headache of thinking through all the implications of that.
---
There are moments when you want to bang people's heads
against the wall and say "listen, this is why Purple are the best band on the planet"
-- Simon Robinson
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1/20/2005, 2:59 pm
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SFGirl
Scribus Administratus
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Registered: 01-2004
Location: Nova Scotia, Canada
Posts: 939
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Re: Planetary parameters
That's a good idea, David, and actually I've already had that headache on another project. I have some very good references on it tucked away in that project's folder, so I should dig those out and have a look. I hadn't thought about that angle (pardon the pun). 
For this story, the how's and why's of the climate are not vitally important, so as long as I have the basic groundwork I should be fine.
off to ponder some more...
Sherry
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Reading: Best of F&SF 50th Edition
Writing: editing "Summer of The Widows"
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1/20/2005, 3:52 pm
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