The headquarters of the European Meteorological Satellite Agency in Darmstadt, Germany (“city of science”!), was easy to spot: It is shaped like one of their early weather satellites, with a central cylinder and protruding wings.

In the gardens outside, large-scale models of their space-borne fleet are lined up among the shrubbery like cocktail tables at a wedding. They are ungainly looking things. Unlike airplanes, whose graceful lines and smooth skins help them slip through the atmosphere, they have delicate protuberances and pocked exteriors. One looks like an engine dipped in gold, another a washing machine with its casing blown off.

It was good to see them there nonetheless. The thing about weather satellites is that they work out of sight. We see them before launch, half under construction, blown out under fluorescent lights and pored over by technicians in bunny suits. Or we see them in artists’ renderings, those sci-fi looking images of spacecraft zooming along in orbit.

Adapted from The Weather Machine: A Journey Inside the Forecast, by Andrew Blum. Buy on Amazon. HarperLuxe

But I went to Darmstadt to see them in a new way, in the moment when they come closest to Earth.

“You know, people are always criticizing the weather predictions,” said Yves Buhler, EUMETSAT’s director of technical and scientific support, when I met him in his sunny corner office. A French rocket scientist, he was dressed like it: crisp white shirt, spread collar, breast pocket full of fine-tipped pens. “But globally, it has become much more accurate. And it has become much more accurate, also, in the medium range—so a week, two weeks. Why is that? Because the satellite observations are providing a uniform coverage of the earth. There’s no black hole of an area.”

Today’s weather forecasts are better than ever before, thanks to continual advances in observing the atmosphere and using those observations for fine-grained computer simulations—“weather models”—capable of confidently predicting future skies, 5, 6, 7, even 8 days in advance.

For today’s weather forecasts, the global view is everything. The outlooks that show up on your smartphone apps, in the television studio screens of on-air meteorologists, or the dispatch centers of airlines, all originate from supercomputer weather models—which are voracious consumers of data. And the best, most global data comes from satellites. But not all weather satellites are equal.

Two categories of weather satellites are flying around Earth today: geostationary orbiters and polar orbiters. The geostationary, or GEOs, orbit in the same direction as Earth’s rotation, making them appear motionless in the sky. They provide constantly updated information about a single area of the atmosphere, and provide the pretty pictures we associate with weather satellites.

The polar, or low Earth orbiters, known as LEOs, fly low and fast. They circle the planet from north to south and south to north, overflying a different geography with each orbit and cutting a pattern around the globe like an orange peeled with a knife. They specialize in quantitative data, sucking up numerical readings of things like temperature and humidity, and feeding them, by the millions, to the supercomputer weather models. When it comes to meaningful impacts on forecasting, especially more than a couple of days in the future, they are the champs.

About the Author Andrew Blum is also the author of Tubes: A Journey to the Center of the Internet

But numbers are hard to see, so it’s the geostationary satellites, the GEOs, and the dramatic images they produce that tend to suck up all the air.

Similarly, not every nation’s weather satellites are the same. This decade, the United States’ geostationary satellite program—GOES—is in the midst of an $11 billion makeover, run by Lockheed Martin. That money pays for the life of four satellites, the first two of which launched in 2016 and 2018, but the number is still shocking, especially when placed alongside the entire annual budget of the National Weather Service, which hovers around a billion dollars annually.

Put more starkly, American weather satellites cost more to fly than the entire forecasting system they support. That expense can be seen as a testament to the importance of satellites to today’s weather forecasts, but it is also a clue to the system’s bureaucratic complexity.