The National Oceanic and Atmospheric Administration's Aircraft Operations Center said the crew of one of the agency's Lockheed WP-3D Orion "hurricane hunter" aircraft was conducting a winter storm flight over the North Atlantic when they encountered what's known as "St. Elmo's Fire."
The fork-shaped discharge of atmospheric electricity is not lightning but has a similar look.
According to Encyclopedia Britannica, the phenomenon, also known as a corona discharge, is “commonly observed on the periphery of propellers and along the wingtips, windshield and nose of aircraft flying in dry snow, in ice crystals or near thunderstorms."
When it appears in a strong electric field in the atmosphere, it's also commonly accompanied by a "cracking or hissing noise."
St. Elmo's fire is typically seen during thunderstorms when the ground below the storm is electrically charged, and there is high voltage in the air between the cloud and the ground, according to Scientific American.
"The voltage tears apart the air molecules and the gas begins to glow," electrical engineer William Beaty notes.
While St. Elmo's fire may not be dangerous to those on the ground, it does give a warning about potentially stormy weather ahead.
Boaters may experience the phenomenon before a lightning strike since marine vessels are often the tallest objects in a large open space and can attract strikes.
"The glow on a masthead produced by an extreme buildup of electrical charge is known as St. Elmo’s Fire," the National Weather Service notes. "Unprotected mariners should immediately move to shelter when this phenomenon occurs. Lightning may strike the mast within five minutes after it begins to glow."
NOAA said the "hurricane hunter" aircraft was deployed to Shannon, Ireland on Jan. 23 to support an ongoing NOAA Satellite and Information Service project to measure ocean surface winds in winter storms over the North Atlantic.
"The project helps NOAA calibrate and validate data collected by weather satellite sensors," according to the agency. "The project also helps scientists and engineers improve the quality and consistency of satellite-based weather data."