Hydrology, invasion biology, areology, ecology, materials science, particle physics, cosmology: all these fields interested Sax extremely, but most of his daily work in these years concerned the weather. Da Vinci Peninsula got a lot of dramatic weather; wet storms swept south down the gulf, dry katabatic winds dropped off the southern highland and out the fjord canyons, initiating big northward waves at sea. Because they were so close to the equator, the perihelion-aphelion cycle affected them much more than the ordinary inclination seasons. Aphelion brought cold weather twenty degrees north of the equator at least, while perihelion cooked the equator as much as the south. In the Januaries and Februaries, sun-warmed southern air lofted into the stratosphere, turned east at the tropopause and joined the jet streams in their circumnavigations. The jet streams were difluent around the Tharsis Bulge; the southern stream carried moisture from Amazonis Bay, and dumped it on Daedalia and Icaria, sometimes even on the western wall of the Argyre Basin mountains, where glaciers were forming. The northern jet stream ran over the Tempe-Mareotis highlands, then blew over the North Sea, picking up the moisture for storm after storm. North of that, over the polar cap, air cooled and fell on the rotating planet, causing surface winds from the northeast. These cold dry winds sometimes shot underneath the warmer wetter air of the temperate westerlies, causing fronts of huge thunderheads to rise over the North Sea, thunderheads twenty kilometers high.

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.