John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
It lasted only a millisecond but was as wide as 26 San Franciscos.
Is this the universe’s way of telling us we all deserve a coffee break? The answer is less spooky, but still weird. The flickering ring recorded by Thomas Ashcraft on June 8 was an ELVE, the necessarily shortened name for Emissions of Light and Very Low Frequency Perturbations due to Electromagnetic Pulse Sources. ELVEs are the ghostly, ephemeral byproducts of thunderstorms, and the average person can generally go through life without seeing a single one.
As usual, Tony Phillips of Spaceweather has the goods on these phenomena:
First seen by cameras on the space shuttle in 1990, ELVEs appear when a pulse of electromagnetic radiation from lightning propagates up toward space and hits the base of Earth’s ionosphere. A faint ring of light marks the broad “spot” where the EMP hits….
ELVEs are elusive—and that’s an understatement. Blinking in and out of existence in only 1/1000th of a second, they are completely invisible to the human eye. For comparison, red sprites tend to last for hundredths of a second and regular lightning can scintillate for a second or more. Their brevity explains why ELVEs are a more recent discovery than other lightning-related phenomenon.
Ashcraft believes this particular ELVE had a diameter of about 186 miles, making it wider than more than two-dozen San Franciscos. It was accompanied by a red sprite, as ELVEs often are, which in this video appears as a transient, electric jellyfish immediately after the doughnut.