After the Flood the oceans’ depth doubled. Where before humanity had understood some tiny proportion of that zone at the top they called pelagic, but now it had grown so vast, encompassing the world in a shroud of sun-dappled blue mystery that no one could ever hope to understand, let alone conquer. As the scientists of the old world watched this fickle, fluid world rise up to conquer their own they supposed that its surface would be an angry maelstrom, believing that only the land had tamed the sea where it stood in the path of currents and broke up the ocean’s mercurial tempers. But this was not to be. With the land finally vanquished and submerged the ocean became a tranquil and placid conqueror, its great depths too solid and stable to sustain the tempests of old. Where once the land had broken up currents, and continents had impinged on the ocean’s majesty, there was nowhere for heat and cold to go. Large gradients of temperature formed between the shallows and the deeps, unmolested by circumnavigating currents. From these gradients grew winds and storms, as if the ocean flung its anger at the irritations of land and people. But now, with the ocean free to move where it willed, heat dissipated from the tropics in every direction, unconcerned by the petty barriers of continents and undersea mountain ranges. Its reign uncontested by the earth, the sea grew complacent. With this change in fluid dynamics the nature of the earth’s storms changed. Storms still rose up, and winds could travel for thousands of kms across the ocean unstopped, driving waves before them; but these winds were not usually very strong, and for much of the earth’s turn the sea was still and quiet. Cyclones still formed in the tropics, and when they did they could travel long distances across huge stretches of warm ocean; but the well-mixed waters of the world ocean ensure that heat cannot gather on the surface, sinking instead to the frozen darkness of the abyss. As a result these cyclones, though long-lasting, tended to be weak, and they never crossed the current barrier of the gyre, where the waters mixed too much to allow heat to gather. But sometimes … Sometimes, in summer, the ocean would still. Perhaps a circumnavigating current would deviate from its usual path, or break for a time. Perhaps the deep churn of water would change under some gravitational, tectonic or tidal influence, and for a short time the surface would be becalmed. Not becalmed so as human communities could notice, but becalmed in such a way that the heat gathered under the tropical sun, over a continent-sized expanse of water. Such confluences of currents are rare, and this becalming might only occur once in a generation. But when the pulse beneath the sea stops like this, a pulse stirs on the surface. The storms gather on this great sheet of hot water, and a storm forms whose power was unheralded before the Flood: a world storm. World storms grow beyond anything humans have ever experienced, covering areas much larger than even the strongest cyclone and moving slowly over the ocean. Whichever direction they head, the vast size of the heated ocean will sustain their power, and they can last for weeks before they finally exhaust their generating power. As they travel, smaller cyclones – mere category 3-5 babies – break off from their flanks, spinning away in random directions to cause havoc of their own, or reforming into secondary monster cyclones in the wake of the main one. The world storm has a power well beyond the traditional system of categorizing cyclones, and usually it invokes its own unique fluid dynamic properties that make a taxonomy of such storms impossible. While such storms rage the weather across much of the hemisphere will change, as they distort the whole atmosphere. In their wake will come an unusual calm, as the ocean temperature equalizes across the range of the storm: winds stop, the sea calms, and the world heaves a sigh of relief. Nothing human can stand in the way of a world storm. Raft communities will be shattered and their inhabitants lost to the tempest. Larger structures too large to capsize will be simply broken apart, smashed by waves no human has ever seen or simply consumed whole if they are close enough to the centre of the whirlwind. Around the edges of the world storm, sometimes thousands of kms from its middle, powerful waterspouts and smaller storms will form, or lightning storms that will destroy anything floating. Communities in the path of the storm, even hundreds of kms away, cannot escape, because the winds being draw towards the world storm will prevent any sailing vessel from escaping. Only the largest, most seaworthy vessels with their own power can hope to leave the storm, and indeed this is the only way a community can survive: pack as many people as possible onto a large, powered vessel while the storm is still spinning up, and flee before it can open its maw and suck in everything living on the surface of the ocean. When a world storm forms, communities in its path will face horrible choices, because they are unlikely to possess enough vessels to liberate everyone. The privileged or the most violent few will rise up and grab what they can, fleeing with the colony’s most precious effects (and maybe their loved ones) to take their chances on the open ocean, knowing that everyone they leave behind them is doomed. Such are the dilemmas of an ocean-going life… World storms have never touched the gyre, though one or two have passed near it. They usually veer northward before they reach it, but if they do come too close they will usually lose their strength as they approach the broken and mixed zone of water around the gyre. History records that one particularly strong world storm managed to partially cross the gyre and spawned a minor cyclone inside, but fortunately the Hulks was at the opposite side of the Gyre at that time, and the Arc weathered the cyclone’s passing without loss of life. Outside the gyre, however, there are few people alive who can say they have weathered such a storm. Rumours abound of structures large enough to weather even this monstrosity, but no one has ever found evidence of such a community… until Captain Dilver of the Gyre discovered and captured the Ziggurat he named Mount Arashi. — Picture credit: I took this picture from the homepage of a fluid dynamics researcher called Gary Davies. He has a blog on fluid dynamics – cool! Check it out! A note on the science of the Flood: I’d originally assumed, like Stephen Baxter’s books, that the world after the Flood would be warmer and more tropical, with all that extra moisture floating around (water vapour is a powerful greenhouse gas). But the extra vast amounts of water should act as a huge heat sink, and I think that this means that the world would actually be meterologically very stable. In the book Baxter talks of a permanent storm like the Eye of Jupiter, but I think that wouldn’t happen because the uninterrupted undersea currents plus huge heat sink effect would prevent the storm conditions required, except in occasional instances when the currents deviate.
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