Radiation clouds may sicken jet travelers.

New Scientist puts the seat backs in the full upright position with the news that there are weird “radioactive zones” in the sky our planes fly through all the time:

We have long known that high-altitude flight exposes us to cosmic rays. The radiation dose on a flight from London to Tokyo is roughly equivalent to a chest X-ray.

Now research flights have revealed the existence of “clouds” where radiation levels can be at least double the usual level. They were discovered as a result of the NASA-funded Automated Radiation Measurements for Aerospace Safety (ARMAS) programme, which aims to develop new methods of measuring and monitoring high-altitude radiation.

In 265 flights, radiation levels detected generally followed the expected pattern, but in at least six instances they surged, as though the aircraft was flying through a radiation cloud.

“We have seen several cases where the exposure is doubled while flying through the cloud,” says ARMAS principal investigator W. Kent Tobiska, of Los Angeles firm Space Environment Technologies.

The surges coincided with geomagnetic storms. This points the finger at energetic electrons being lost from the outer Van Allen radiation belts, where charged particles mostly from the solar wind are trapped by Earth’s magnetic field.

Tobiska believes that such a storm can liberate electrons trapped in the Van Allen belts. “Those electrons are driven into the upper atmosphere, collide with nitrogen and oxygen atoms and molecules, and then create a spray of secondary and tertiary radiation, likely in the form of gamma rays.”