Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our
      fascinating universe is featured, along with a brief explanation
                    written by a professional astronomer.

                               2020 August 11

                         Churning Clouds on Jupiter
    Image Credit & License: NASA/JPL-Caltech/SwRI/MSSS; Processing: Kevin
                                   M. Gill

   Explanation: Where is Jupiter's ammonia? Gaseous ammonia was expected
   to be seen in Jupiter's upper atmosphere by the orbiting Juno
   spacecraft -- but in many clouds is almost absent. Recent Juno data,
   however, gives some clues: some high-level clouds appear to be home to
   an unexpected type of electrical discharge dubbed shallow lightning.
   Great charge separations are needed for lightning, which might be
   created by colliding mushballs lifted by rising updrafts of gas.
   Ammonia and water stick to these mushballs which rise until they get
   too heavy -- after which they fall deep into Jupiter's atmosphere and
   melt. By this process, ammonia found missing from Jupiter's upper
   atmosphere reappears below. Pictured by Juno, churning clouds on
   Jupiter show not only mesmerizing complexity but some high-level,
   light-colored pop-up clouds. Understanding atmospheric dynamics on
   Jupiter gives valuable perspective to similar atmospheric and lightning
   phenomena that occur on our home Earth.

                 Peaking Tonight: The Perseid Meteor Shower
              Tomorrow's picture: Comet NEOWISE's Pointing Tail
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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