Storms in the tropics have been observed emitting medium-duration gamma rays, challenging established understandings of the phenomena associated with lightning.
A recent investigation conducted by a team of researchers utilizing a modified reconnaissance aircraft has revealed that thunderstorms in tropical regions possess radioactive characteristics.
This morning, the team’s research findings were disseminated through two papers in the esteemed journal Nature. One of the studies elucidates the recurrent release of prolonged gamma-ray luminescence throughout extensive regions of the atmosphere amidst tropical thunderstorms. The subsequent paper delves into the intricacies of a newly recognized phenomenon—termed flickering gamma-ray flashes, or FGFs—and contemplates the connection between these flashes and various manifestations of gamma radiation emanating from thunderclouds.
“FGFs are generally significantly less intense than the widely recognized Terrestrial Gamma-ray Flashes (TGF) that have been observed from space since the 1990s,” stated Martino Marisaldi, a physicist at the University of Bergen in Norway and lead author of one of the papers (and co-author of the other), in an email to Gizmodo. “This illustrates the necessity of approaching the thundercloud (potentially from above, as we experienced) to discern their presence.”
The team employed a NASA-owned reconnaissance aircraft to ascend above tropical thunderstorms and observe the gamma radiation emitted by these meteorological phenomena. The aircraft—an ER-2, a modified variant of Lockheed Martin’s U-2—identified gamma-ray emissions that persisted for hours, encompassing an expanse of nearly 3,500 square miles (9,065 square kilometers).
The phenomena of gamma-ray glows and terrestrial flashes have long been associated with thunderstorms; however, the recently identified FGFs represent a unique category of radiation, exhibiting durations that surpass those of terrestrial bursts while remaining significantly shorter than the glows themselves.
“FGFs exhibit significant distinctions from both TGFs and glows, yet they retain certain characteristics of each,” Marisaldi stated. “This is the rationale behind our characterization of them as the intermediary between the two phenomena.” FGFs exhibit radio silence; however, they are frequently succeeded, within mere milliseconds, by radio pulses known as Narrow Bipolar Events (NBE), which are commonly linked to the onset of lightning. Consequently, it is fascinating to propose a causal relationship between the two phenomena.
Prior investigations that collected gamma radiation data from thunderstorms via space have established a correlation between terrestrial gamma-ray flashes and the frequency with which these gamma emissions occurred prior to lightning strikes. Utilizing the spy plane, the recent team identified more than 100 TGFs that were insufficiently robust to be detected from the ground.
“This indicates that the TGF lightning ratio is not 1-to-10000 as determined from space observations, but rather 1-to-100 or potentially even greater,” stated Nikolai Østgaard, a physicist at the University of Bergen and lead author of one of the papers (and co-author of the other), in an email to Gizmodo. “All the ephemeral phenomena (TGF: microseconds, FGF and glow burst: tens of milliseconds) were succeeded by vigorous lightning activity, and may contribute significantly to the initiation of lightning.”
Lightning represents a discharge of electricity within the Earth’s atmosphere, manifesting either as a phenomenon that remains aloft or as striking tendrils of energy that connect with the ground. Despite the occurrence of approximately 40,000 thunderstorms on Earth daily, the phenomenon of lightning, frequently generated by these storms, continues to elude comprehensive understanding.
“The glows, which generally persisted for mere seconds, exhibited remarkable dynamism, rising as if the storm were a seething cauldron — challenging the notion that glows are characterized by gradual changes and lack distinct features,” remarked Joseph Dwyer, a physicist at the University of New Hampshire at Durham, in a related News & Views article. “The flickering gamma-ray flashes bear a resemblance to the multi-pulsed terrestrial gamma-ray flashes observed from satellites, indicating a potential common mechanism underlying this diverse array of energetic phenomena.”
Dwyer stated that the team’s research “effectively rules out” alternative proposed mechanisms for the initiation of lightning, such as cosmic rays and lightning leaders. Dwyer remarked that positron feedback is “the last mechanism standing.”
The recent study establishes a foundational framework for elucidating the connection between gamma outbursts and thunderclouds, alongside the phenomena of lightning and its origins. The recent observations of gamma flashes occurring in the absence of lightning suggest that electrified storms possess the inherent ability to generate gamma rays.
The team’s findings are not entirely surprising; aside from lightning, various forms of gamma radiation had already been documented in relation to tropical storms. However, the recent research elaborates on an increasingly intricate depiction of thunderclouds, which are among the most astonishing natural phenomena on our planet.
ALSO READ:
John Amos, The Patriarch In The Pioneering Sitcom Good Times, Has Passed Away At The Age Of 84.
