In peace, observing the weather is utility work, like swabbing the decks and trimming the trees. But in war, observations become secrets, and weather forecasts are weaponized. The desperation for them has led to expanded networks and new technologies.World War II marked the beginning of a transformation of weather observation from a collection of disparate points into a global system — made up of observatories on the ground, in the air and, soon enough, in space. But it happened piece by piece, driven by technological developments and military needs.The fighting in the North Atlantic stretched from Labrador and Greenland in the west, to Svalbard and Franz Josef Land in the Barents Sea, all the way east to Novaya Zemlya, which separates the Barents from the Kara, north of Siberia. Throughout, the Germans were at a distinct meteorological disadvantage. The Allies predominantly held the northerly and westerly positions, while storms tend to move from west to east and from north to south.Before the war, remote whaling stations in Greenland and Iceland would radio observations for the benefit of ships throughout the region. But just as the Civil War broke apart the Smithsonian’s early observation network in the United States, World War II halted the exchange of weather data across the North Atlantic.The Nazi weather service, known as the Wetterdienst, moved quickly to compensate, sailing observation ships up the North Sea and into the Arctic, with a meteorologist onboard to launch balloons. When the Allies began to sink the unarmed ships, the Wetterdienst turned to new technological solutions.The Siemens-Schuckertwerke corporation — predecessor to today’s Siemens conglomerate — developed an automatic weather observatory, code-named Kröte, or “toad,” with nickel-cadmium batteries and a powerful radio to transmit readings. The earliest versions were small enough to be delivered to remote locations by airplane, but keeping them hidden and operating was a challenge.The first toad, deployed on the Norwegian island of Spitsbergen in 1942, was quickly found and dismantled. The second, on Bear Island, had its antenna destroyed by bears. With more than 200 U-boats patrolling the North Atlantic, working to maintain the blockade of England, the Germans’ need for weather observations became desperate.By the fall of 1943, Siemens had developed a new version of the toad with a 10-metre antenna, powerful enough to broadcast encoded observations all the way from the North American coast to receiving stations in Europe, but small enough to fit inside a submarine’s torpedo tubes.U-537, sent to install it, sailed from its concrete pen in Bergen, Norway, on the night of Sept. 30, 1943. Its destination was a spot near the present-day border between Labrador and Quebec — a location the captain hoped would be far enough south to be free of ice and far enough north to be free of locals.A photograph, unearthed from the military archives in the 1970s, captures the scene upon their arrival in North America: seven sailors in black knit caps standing around two rubber dinghies laid askew on the U-boat’s deck. Working in the autumn fog, they lugged 10 grey canisters, each the size of a large bucket and weighing 200 pounds, to the top of a nearby hill. When they had finished assembling the system, they hand-painted “Canadian Meteor Service” on the canisters and littered the site with American cigarette packs.Even today, with the familiarity of satellite communications, solar panels and small sensors everywhere, it seems an audacious idea: a clandestine intercontinental automatic weather station, a Wetter-Funkgerät Land. Given the designation WFL-26, the remote weather station broadcast for less than a month before its transmissions were mysteriously jammed.And then it disappeared for 40 years. A U.S. Navy team missed it in 1952 while scouting the area for places to install the massive radars of the DEW Line, the Distant Early Warning network, built to watch for Soviet long-range bombers. A Canadian geomorphologist stumbled upon it in 1977 but assumed it was, in fact, what it said to be on the can: an automated Canadian Weather Bureau station.It was only after a retired Siemens employee and historian, Franz Selinger, noticed the unusual landscape in the photographs that accompanied the logbook of U-537 that anyone went looking for it at all. Sailing on a Canadian icebreaker, he and a Canadian military historian finally found it in 1981, systematically vandalized, its connections cut and contents strewn across the rocky ridge. Today, “Weather Station Kurt” — as it became known, named after its government minder, Kurt Sommermeyer — is on display at the Canadian War Museum in Ottawa, looking grey and ugly, like so many weapons. (U-537, for its part, is at the bottom of the Pacific, sunk in 1945 by the submarine USS Flounder.)It’s a wild story — an act of meteorological desperation and technological bravado begging for Hollywood. But it marks a pivot point in the history of weather observation.For the first century of telegraph-based observation networks, meteorologists were preoccupied with expanding their reach, occupying lighthouses, ships and airfields. The war cut the map in half. But it enabled new technological advances that raised the possibility of a newly expansive view of the weather.For the hundred years before Weather Station Kurt, the telegraph allowed for news of the weather to be transmitted faster than the weather itself. But someone had to be there. (Often, somebody still does, as on the Norwegian island of Utsira.) Kurt was the proto-example of a new kind of station, capable of working on its own. Soon, these observatories would not only be in remote corners of the Atlantic but high up above the earth.Another Nazi technology opened up new possibilities for observing from the sky. In the final months of the war, Wernher von Braun, the German rocket engineer, made a terrifying and deadly technological leap, successfully launching the first guided missile, known as the V-2, or “vengeance weapon.” It was horribly inaccurate, flying far wide of its intended targets, but still killed 9,000 people in London, Antwerp and Liège.After the war, the United States and the Soviet Union famously scrambled to collect the remaining rockets and the scientists who designed them, and von Braun was brought to the United States. In the earliest days of the Cold War, their priority was adapting the V-2 for continued military use — and indeed, its design would serve as the basis for both Soviet and American rockets eventually capable of carrying nuclear warheads, and astronauts, to space. But first they would be used to observe the weather.In October 1946, technicians at the White Sands Proving Ground in Nevada installed a camera in the nose cone of a captured V-2 and launched it straight up into the sky. Within 30 seconds, the rocket disappeared from view. But then it began looking back, its 35-mm camera snapping photographs every second and a half, up to an altitude of 83 miles, before crashing down to the desert. A search plane found the wreckage and recovered the film, protected in a cylindrical steel cassette the diameter of a dinner plate.“A truly dramatic spectacle unfolded when the film was developed,” the camera’s designer, Clyde T. Holliday, recalled. “On these photographs we saw what a passenger on a V-2 would see if he could stay alive on the zooming ride up to that height and back again, and how our earth would look to visitors from another planet coming in on a spaceship.”It was a view that had before been only imagined, but its practical benefits were unmistakable. This first visit of a camera to the margins of space yielded photographs of a quarter of the United States, an area of nearly a million square miles. The curvature of the earth was visible, along with bands of clouds stretching hundreds of miles in rows like streets.Meteorologists were immediately enthralled by the possibilities. The director of the Weather Bureau, Francis Reichelderfer, wanted reprints of the images from the camera’s designers at the Applied Physics Lab at Johns Hopkins University to be shared with every weather office in the country, “so our forecasters can obtain a glimpse into what may well turn into a potent weather forecast tool in the future.” Excerpt from The Weather Machine by Andrew Blum ©2019. Published by HarperCollins Publishers Ltd. All rights reserved.