An unexpected discovery reveals that energy from lightning can reach the highest layers of the atmosphere, posing potential risks to satellites and astronauts.
When lightning strikes, it generates unique electromagnetic waves known as whistlers, named for their ability to be converted into sound signals. For many years, scientists believed that these lightning-induced whistlers were confined to altitudes below 1,000 kilometers above Earth’s surface.
However, researchers from the University of Alaska Fairbanks have identified that some whistlers can reflect off the ionosphere, a layer saturated with charged particles. This reflection enables the waves and the energy they transport to ascend to altitudes as high as 20,000 kilometers, extending into the magnetosphere, the domain influenced by Earth’s magnetic field.
Evidence of these reflected whistlers has been observed in data collected by the Van Allen Probes, which analyzed the magnetosphere between 2012 and 2019. Additionally, patterns consistent with this occurrence were noted in studies dating back to the 1960s, indicating that this phenomenon is both frequent and ongoing, according to the researchers.
The energy contributed by lightning to this atmospheric region could be significantly greater than previously estimated, potentially reaching twice as much. This energy not only accelerates nearby particles but can also generate electromagnetic radiation that poses threats to satellites and the well-being of astronauts.
“Lightning was always regarded as a minor contributor,” comments a researcher involved in the study. “With the data available only in the past decade, we are beginning to analyze this phenomenon in unprecedented detail.” This emerging research invites further investigation to enhance our understanding of the magnetosphere.
Linking lightning occurrences to the magnetosphere is crucial, especially as climate changes may lead to an increase in lightning-prone storms, according to the researchers. The team plans to further analyze data from additional satellites to gain insights into the impact of lightning-based whistlers within the magnetosphere and their responses to space weather.
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