As a point of accuracy, angle of repose is a civil engineering term referring to how steep a slope is possible without slumping due to gravity. The angle varies according to the material under consideration.

I am completely misusing the term here in reference to axial tilt because it sounds so good. So sue me.

Today is December 30; the year is near it’s end. The solstice was December 22 this year, so the days have been getting longer for eight days now. What we call the first day of winter is actually winter’s mid-point, judged by the inclination of the Earth. The “incorrect” way we measure winter actually works pretty well though, because there is a delay effect between tilt and the weather that depends on it.

“The Earth tilts south in the winter and tilts back north in the summer.” Easy to say and easy to understand, just like saying that the Earth is flat, but of course it’s wrong. I remember teaching the matter to my school kids every year. I would designate a student sitting in the center of the room as the Sun and walk around the classroom with the globe tilted roughly 23 degrees toward the bank of windows to demonstrate that the angle of inclination doesn’t change, only the position of the Earth in relation to the Sun. I’m sure they all forgot it by the next day.

The seasons as we know them are due to the degree of tilt. Tilt further, and the seasons would be more extreme. Tilt less and they would be less extreme. I’ve made a career of writing about that.

My first novel, Jandrax, was set on a world circling a cool sun, with a tilt of something like 32 degrees. That made for seasons like those on Earth, but more extreme. It worked out well for my intentions, stranding a bunch of religious extremists and watching them adapt in two different ways, as a static civilization in changing weather, and as nomads who followed the good season.

The unharmonious planet Harmony was in the middle of an ice age, with the only livable real estate flanking the equator, and of course they had two summers and two winters each year.

No, I know it isn’t obvious, but it is real. I explained the phenomenon in 14. Axial Tilt. Check if you doubt me.

Cyan came later. I set it up as a planet with virtually no tilt, resulting in unlivable cold, miserable cold, too cold for comfort, Goldilocks perfect, too hot for comfort, miserably hot, and too hot to live, all depending on your latitude. That would have made for a perfect climate somewhere (a boring thought for a writer) except that I threw in a 40 hour day so even at the “perfect” latitude you could count on burning your brain and frosting your buns every overlong day of the seemingly endless year.

It also resulted in two virtually independent super-biomes, separated by a dead torrid zone, as Keir lamented when Tasmeen, Beryl, Debra, and Viki . . .; no, sorry, you’ll have to read that yourself.

Okay, what’s opposite of the unchanging, tilt-less Cyan? A planet of Uranian orientation, of course. Stormking becomes the third of the trilogy, lying on its back in orbit, presenting first one pole and then the other to its star. Such a planet would probably not be viable for a human civilization, but as a place for an orbiting civilization to dump its exiles, it’s perfect.

Dome cities could survive on a Uranian planet, but why would they want to? Any people, like our exiles, who actually interact with the environment would have to keep continually on the run. That’s a little like the nomads of Jandrax, but where those were a people whose march kept them on the leading edge of a moving paradise, the exiles of Stormking live in an endless hell-storm. All of the water of that planet spends half of the year locked up in north polar ice caps while the south pole is desert. Then all that water has to move from north pole to south to freeze again while the north pole becomes desert. All this will have to happen twice a year.

You can’t imagine the storms. Actually, you don’t have to. I do, and then I have to write them.

This is going to be fun.