Effects of severe radiation storms?

Question

I’ve got this planet that orbits it’s star slightly closer than earth orbits the sun. For story reasons I need it to have small yet severe radiation storms and I was thinking that either a weak or fluctuating magnetic field could cause them. The more pressing question is how would they effect the atmosphere and the surface of the planet. I don’t need to know what they would do to organic matter because that’s fairly obvious, they’d do what all radiation does.

Some more specifics:

The star the planet orbits is orange, so the majority of its output is on the lower end of the EM spectrum.

The radiation storms are common but not every day. Probably 2-5 are normal in a year, and mostly in desert regions.

The radiation isn’t strong enough to render an area uninhabitable for long periods of time, maybe a few weeks at most.

The radiation does not penetrate more than a few meters into stone.

So what would radiation storms like the one I’ve described above do if they struck one of this planet’s deserts? I’d also be interested to hear any ideas on what they would look like as they swept across the landscape.

Answer 1

The Ugly, the Bad, and the Good

The Ugly

I don't know what you mean by "radiation storm." I'm going to make an assumption ("the Bad"), but the phrase sounds more like Star Trek technobabble than an actual atronomical or meterological event. Therefore, if you find no value in my answer, then I strongly recommend you specifically describe what you mean by "radiation storm."

The Bad

My assumption for a "radiation storm" is this: Somehow, a pinhole forms in the planet's magnetosphere, upsetting the Van Allen radiation belt, such that a small geographic area is bombarded by the Solar Wind and cosmic rays.

A "small geographic area" is probably the size of Kansas. But you can handwave this.

What would happen? Basically the same thing that happens in a microwave. You'd cook everything, probably sterilizing the ground. In a desert, you might melt the silicates, turning the surface into a thin layer of glass.

But, that might not be what you want. So, let's think about this a bit...

Radiation vs. Radioactive

Part of the problem here is the difference between radiation and radioactive. When a nuclear bomb goes off, most of what the world experiences is radiation, which passes through everything (leaving sunburns, cancer and death in its wake) but is thereafter gone.

Radioactive, on the other hand, is an adjective applied to particles (like plutonium) that are also spread by the explosion. Radioactive particles are spread like snow and last between hours and centuries depending on exactly what particle has been left behind.

As was pointed out to me months ago, radiation does not breed radiation. If it did, your microwaved food would become radioactive.

Therefore, the only way to leave radiation behind as a consequence of the "radiation storm" is for that storm to be comprised of radioactive particles, which is pretty much never what you get from outer space.

So, long story short, if you're trying to create temporary radioactive wastelands due to these "radiation storms," you need to provide a source of radioactive particles. The source must be regularly producing these particles or they will die out on their own. I could be wrong, but generally speaking, I don't think suns do this.

The Good

But, what if you have a binary star system: your orange star and a small pulsar. Pulsars in a binary system pull material (radioactive material) from the other star — but let's tilt the pulsar's axis such that the emission beams occasionally sweep some of that radioative material out into the orbital plane ... where it periodically meets up with your now defensless planet (because the Van Allen belts were designed to stop really light radiation, not really heavy radioactive particles).

Answer 2

You might be interested in this.

Storms Generate Thunder, Lightning and…Antimatter?

Scientists had also conjectured that gamma rays from lightning could trigger “photonuclear” reactions that can break atoms apart. For example, stable nitrogen-14 atoms could in theory absorb gamma rays and spit out neutrons to become unstable nitrogen-13 atoms, which could in turn give off positrons and neutrinos and radioactively decaying to become more stable carbon-13 atoms.

Now researchers in Japan say they have the first proof that gamma rays from lightning can trigger such nuclear reactions. “We provided clear and conclusive evidence for both neutrons and positrons from a single event that can be only explained by photonuclear reactions from lightning,” said study lead author Teruaki Enoto, a high-energy astrophysicist at Kyoto University. The scientists detailed their findings in the Nov. 23 issue of the journal Nature.

Further

These findings suggest that lightning can generate radioactive isotopes of carbon, nitrogen and oxygen in Earth’s atmosphere. “It would be interesting to know what fraction of isotopes in the atmosphere are generated by lighting discharges,” Enoto said.

If the thunderstorms are severe and prolonged enough, there is no reason why they could not produce the severe radiation storms you are asking for. The added benefit is that they would produce prodigious amounts of ozone, which itself is an environmental toxin.