Over the course of 12 passes, Juno detected 613 lightning microwave pulses, with powers ranging from about the same as lightning on Earth to at least 100 times that. There is uncertainty in the interplanetary comparison, so Jupiter’s lightning may have been a million times more powerful than Earth’s.
Lightning on Jupiter is likely caused by a mechanism similar to what happens within Earth’s atmosphere, where ice crystals within clouds gain an electrical charge, and voltage differentials lead to cloud-to-cloud or cloud-to-ground lightning strikes.
There are also notable differences between the planets. There is no true surface on Jupiter and ice crystals within the Jovian atmosphere contain water and ammonia. On Earth, it’s just water. Atmospheric convection also works differently on Jupiter, where moist air wants to sink because it is heavier than the hydrogen-rich atmosphere around it. Nitrogen, heavier than water, dominates Earth’s atmosphere, so moist air rises.
Therefore, it is not just Jupiter’s immense size that causes such large and powerful storms. Much more energy is required to push moist air upward, resulting in stronger winds and more intense cloud-to-cloud lightning. There is still a mystery about what makes lightning strikes so extreme on Jupiter.
“Could the key difference be hydrogen atmospheres versus nitrogen atmospheres, or could it be that the storms are higher on Jupiter and therefore greater distances are involved?” said Michael Wong, a planetary scientist at the Space Sciences Laboratory at the University of California, Berkeley. Wong is the lead author of the Jupiter lightning study.
“Or could it be that there is more energy available because with moist convection on Jupiter, more heat buildup is needed before the storm can be generated to create lightning?” Wong said in a press release. “It’s an active area of research.”
