Those were the major patterns in Martian weather: violent around aphelion, gentle during the helionequinoxes; the south the hemisphere of extremes, the north of moderation. Or so some models suggested. Sax liked generating the simulations that created such models, but he was aware that their match with reality was approximate at best; every year on record was an exception of some kind, with conditions changing at each stage of the terraforming. And the future of their climate was impossible to predict, even if one froze the variables and pretended terraformation had stabilized, which it certainly had not. Over and over Sax watched a thousand years of weather, altering variables in the models, and every time a completely different millennium flitted past. Fascinating. The light gravity and the resulting scale height of the atmosphere, the vast vertical relief of the surface, the presence of the North Sea that might or might not ice over, the thickening air, the perihelion-aphelion cycle, which was an eccentricity that was slowly precessing through the inclination seasons; these had predictable effects, perhaps, but in combination they made Martian weather a very hard thing to understand, and the more he watched, the less Sax felt they knew. But it was fascinating, and he could watch the iterations play out all day long.

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Or else just sit out on Simshal Point, watching clouds flow across hyacinth skies. Kasei Fjord, off to the northwest, was a wind tunnel for the strongest katabatic blows on the planet, winds pouring out of it onto Chryse Gulf at speeds that occasionally reached five hundred kilometers an hour. When these howlers struck Sax could see the cinnamon clouds marking them, over the horizon to the north. Ten or twelve hours later big swells would roll in from the north, and rise up and hammer the sea cliffs, fifty-meter-high wedges of water blasting to spray against the rock, until the air all over the peninsula was a thick white mist. It was dangerous to be at sea during a howler, as he had found out once while sailing the coastal waters of the southern gulf, in a little catamaran he had learned to operate.