What HAARP actually does, and the 85 kilometres it cannot reach
2026-07-19 · EA5IYR
There is a facility in Alaska called HAARP that points a few megawatts of shortwave straight up. There is one near Tromsø in Norway called EISCAT, and one at Vasilsursk in Russia called Sura.
They are ionospheric heaters, they are genuinely interesting, and one of them has become the most reliably blamed object on the internet. What they are for
The ionosphere is a plasma, and plasma physics is difficult to study because you cannot put the ionosphere in a laboratory.
So instead you go the other way: illuminate a patch of it with enough HF energy to raise the electron temperature slightly, and watch what happens. Researchers have used this to produce artificial airglow, to create density structures on demand, and to generate ELF and VLF waves by modulating currents that already flow up there — which is a genuinely elegant trick, because a VLF antenna on the ground has to be kilometres long and this one is made of sky.
This is not new physics. It has been known since 1933, when listeners across Europe began hearing one station underneath another and the ionosphere stopped being thought of as a passive mirror.
The point is control. Nature produces these effects constantly and unpredictably; a heater produces them where you are pointing an instrument, when you are ready. Why the weather claim does not work
Two reasons, and the first is in the diagram.
Altitude. Weather happens in the troposphere, from the ground to about 15 km. Heaters work on the ionosphere, from about 100 km up. There is roughly 85 kilometres of nothing in between — air too thin to carry weather and too far below the plasma to be part of it. The Space Station orbits inside the region being heated. It is not raining there.
Energy. A heater radiates a few megawatts, briefly, into a patch. The sun deposits energy into the upper atmosphere continuously at a scale larger by many orders of magnitude, and a hurricane releases more energy in a second than every heater on Earth running for a year. The budget is not close. Why the story is durable anyway
Because it begins with something true.
HAARP does heat the upper atmosphere. It is partly military-funded. It was, for years, not much explained to the public. Those are real facts, and a theory built on real facts travels much further than one built on nothing.
The leap is from it modifies the ionosphere to it modifies the weather, and that leap crosses 85 km of atmosphere and several orders of magnitude of energy without stopping. Naming a real mechanism is not the same as showing it does the thing claimed. What you can actually observe
If you want to see a heater's effect for yourself, the honest answer is: with difficulty, and by looking at the ionosphere.
Amateur experimenters have detected the ELF and VLF signals generated by modulated heating. Optical observers have photographed artificial airglow over Alaska. Both are real results, both are small, and both live entirely up where the ionosphere is already doing far larger things on its own.
That is the honest shape of it. A real instrument, doing real and fairly subtle science, in a place that has nothing to do with the sky you can see.
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Sources: Physics Today — HAARP, the most powerful ionosphere heater on Earth, University of Florida — ionospheric modification, AAP FactCheck — HAARP weather control conspiracy, RMIT FactLab — claims of weather manipulation are nonsense.