The southern hemisphere, being more uniform than the north, had winds that followed even more clearly the physics of air over a rotating sphere: southeast trades from the equator to latitude thirty; prevailing westerlies from latitude thirty down to latitude sixty; polar easterlies from there to the pole. There were vast deserts in the south, especially between latitude fifteen and thirty, where the air that rose at the equator sank again, causing high air pressure and hot air that held a lot of water vapor without condensing; it hardly ever rained in this band, which included the hyperarid provinces of Solis, Noachis, and Hesperia. In these regions the winds picked up dust off the dry land, and the dust storms, while more localized than before, were also thicker, as Sax had witnessed himself, unfortunately, while up on Tyrrhena with Nirgal.
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.
• • •
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.
Nicer by far to observe storms from the sea cliffs. No howler today; just a steady stiff wind, and the distant black broom of a squall on the water north of Copernicus, and the heat of sun on skin. Global average temperature changed every year, up and down, mostly up. With time as the horizontal axis, a rising mountain range. The Year Without Summer, now an old chasm; actually it had lasted three years, but people would not disturb such a name for a mere fact. Three Unusually Cold Years— no. It didn’t have what people wanted, some kind of compression of the truth, to create a strong trace in the memory, perhaps. Symbolic thinking; people needed things thrown together. Sax knew this because he spent a lot of time in Sabishii visiting Michel and Maya. People loved drama. Maya more than most, perhaps, but it served to show. Limit-case demonstration of the norm. He worried about her effect on Michel. Michel seemed not to be enjoying life. Nostalgia, from the Greek nostos, “a return home,” and algos, “pain.” Pain of the return home. A very accurate description; despite their blurs, words could sometimes be so exact. It was a paradox until you looked into how the brain worked, then it became less surprising. A model of the mind’s interaction with physical reality, blurred at the edges. Even science had to admit it. Not that this meant giving up trying to explain things!
“Come out and do some field studies with me,” he would urge Michel.
“Soon.”
“Concentrate on the moment,” Sax suggested. “Each moment is its own reality. It has its particular thisness. You can’t predict, but you can explain. Or try. If you are observant, and lucky, you can say, this is why this is happening! It’s very interesting!”
“Sax. When did you become such a poet?”
Sax did not know how to answer that. Michel was still stuffed with his immense nostalgia. Finally Sax said, “Make time to come out into the field.”