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Thunderstorms over Jupiter are so strong that ammonia-rich hail known as “mushballs” can fall from the sky.
New observations from NASA’s Juno spacecraft on the gas giant planet could have implications for our understanding of the atmospheres of giant planets in general, which are largely made up of gas and are subjected to much higher pressures than is expected. we know on Earth.
These observations also suggest that Jupiter has “shallow lightning,” which occurs in clouds containing ammonia and water. It’s quite different from Earth, where lightning comes from clouds of water, according to a NASA statement.
Related: In photos: Juno’s breathtaking view of Jupiter
“Juno’s close flyovers of cloud tops allowed us to see something surprising – smaller, shallower lightning – coming from much higher altitudes in Jupiter’s atmosphere than previously assumed.” Heidi Becker, head of the Juno radiation monitoring investigation at NASA’s Jet Propulsion Laboratory in California, said in the same statement. Becker is also the principal author of a new paper in Nature, one of three new studies describing Juno’s work.
Thunderstorms over Jupiter and Earth have one thing in common: these natural phenomena cause water to move in the atmospheres of both planets. When NASA’s Voyager spacecraft first spotted lightning in Jupiter in 1979, both planets were thought to have similar lightning.
Voyager spotted lightning in the tops of Jupiter’s clouds, suggesting that the phenomenon originated from deep water clouds. Juno’s new observations of nighttime flashes to Jupiter, however, reveal a more subtle story.
On Jupiter, thunderstorms are thought to form about 50 km below the visible bands and storms on the planet, where temperatures are near the freezing point of water. Some of these storms are so powerful that they drag crystal-clear water ice into the planet’s upper atmosphere.
“At these altitudes, ammonia acts as an antifreeze, lowering the melting point of water ice and allowing a cloud to form with an ammonia-water liquid,” Becker added in the same statement. “In this new state, droplets of ammonia-water liquid can collide with the rising ice-water crystals and electrify clouds. It was a big surprise, because ammonia-water clouds do not exist. on earth.”
Shallow lightning can also show why ammonia appears to be absent (or depleted) from Jupiter’s atmosphere, and why ammonia appears at different concentrations in Jupiter’s atmosphere.
“Scientists used to realize that small pockets of ammonia were missing, but no one realized how deep those pockets were or whether they covered most of Jupiter,” Scott said. Bolton, Juno principal investigator at the Southwest Research Institute in San Antonio. declaration.
“We had a hard time explaining the ammonia depletion just by the ammonia and water rain,” Bolton added, “but the rain couldn’t go deep enough to match the observations. I realized that a solid, like hail, could go deeper and take more ammonia. When Heidi discovered shallow lightning bolts, we realized we had some evidence that ammonia mixed with water high in the atmosphere, and therefore lightning was a key piece of the puzzle. “
Mushballs and depleted ammonia are described in more detail in work published in the Journal of Geophysical Research: Planets in two parts, available here and here. When ice crystals combine with ammonia (a substance abundant in Jupiter’s atmosphere), the ammonia creates an “antifreeze” effect and turns the ammonia in the ice into liquid.
When the fungi fall into Jupiter’s lower atmosphere, they carry ammonia and water with them before finally evaporating in warmer temperatures. “This explains why we don’t see a lot of them in these places with the Juno microwave radiometer”, Tristan Guillot, Juno co-researcher at the University of the Côte d’Azur in Nice, France, and lead author of the two parts paper on ammonia and mushballs, said in the NASA press release.
“As it turns out, the ammonia isn’t really lacking; it’s just carried in disguise, having concealed itself by mixing with water,” Bolton added. “The solution is very simple and elegant with this theory: when water and ammonia are in a liquid state, they are invisible to us until they reach a depth where they evaporate – and that is is quite deep. “
Juno arrived in Jupiter almost exactly four years ago, on July 4, 2016, to better understand the origin and evolution of the planet. Juno’s findings not only inform our understanding of the planets in the solar system, but also gas giant exoplanets, especially those of similar size and formation history to planets in our solar system.
Editor’s Note: This article has been updated with new information, videos and images from NASA.
Follow Elizabeth Howell on Twitter @howellspace. follow us on Twitter @Spacedotcom and on Facebook.
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