Fwd: Re: Day length

From: Grimmund <grimmund_at_Qy5VKWfJYnPRREm0ltaxBq2FIhWJ9NOPivgH4-TadkNvw4Guu1dB45J52dcmsQcAr4p>
Date: Thu, 3 Jan 2008 10:58:50 -0600

Well met!

> Which is due, of course, to the fact that the sun is hotter (and
> brighter, and larger) in the summer and colder (and dimmer) in the winter.

Mythic, but OK. It's a simple explanation. I don't know if it's necessary to cycle the solar power level; if the days are longer in summer and shorter in winter, the different weather may simply be due to getting more solar energy in summer and less in winter-just like on earth.

If the solar heat's on for 16 hours, and off for 8, you get warmer weather. If the solar heats on for 8 hours and off for 16, you get cooler weather, without having to jigger the heater output.

> >Yelm's path arcs far up north during summer, and far down south
> > during winter (so it can actally be Summer in Pamaltela when it's
> > winter in Genertela).
> The sun does move its arc north in the summer and south in the winter,
> in relation to the sky dome; AND the dome tilts farther south---much
> farther---in the winter.

OK. These two explanations appear to be mutually exclusive. One explains seasons in terms of varying solar output, one in terms of varying solar paths (like axial tilt on earth.) Varying the solar path contradicts the statement that the sun appears directly overhead everywhere at noon.

I was under the impression that the calender and seasons were the same everywhere on Glorantha, with the entire lozenge experiencing the same seasons at the same time . Cycling solar output up and down (directly, or by length of day, or both) explains that nicely. It also fits with everyone on Glorantha using the same seasonal calender, which only makes sense if everyone is experiencing the same seasons at the same time.

Likewise, I was under the impression that length of day varies with the seasons, but it does so uniformly, all across the lozenge, explained in simple terms that the sun really DOES take longer to cross in summer than in winter. My working assumption has been that nights are correspondingly shorter or longer, and the total day duration (noon to noon) stays the same, regardless of how it breaks up into daylight and night.

On the other hand...

Generating seasons by tilting the solar path seasonally north or south of the center line would cause seasons to be opposite each other, depending on where the sun is, as on earth. If this were true, there would be no reason for Pamaltela and Genertela to use the same seasonal calender. Their seasons are reversed.

On Earth, though, this works (in part) because the earth is so large. You don't really get noticeable seasons until you get past the tropical zone that extends 23 degrees north/south of the equator, that being the farthest north/south the sun will appear directly overhead. Seasonal influence develops slowly from there to the pole.

Given Gorantha's relatively tiny size, if it were on earth, it'd be all tropical, extending about 14 degrees above and below the equator. My first impression would be that using a variable solar path to drive seasons would be difficult to make work.




"A word to the wise ain't necessary - it's the stupid ones that need
the advice."  -Bill Cosby


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