NASA currently has a spacecraft orbiting Jupiter called Juno. Recent data collected from Juno suggests that the massive planet is home to a phenomenon known as “shallow lightning.” This is an unexpected form of electrical discharge that originates from clouds that contain an ammonia-water solution. Lightning on Earth originates from clouds containing water.
Other Juno findings suggest that violent thunderstorms the gas giant is known for form slushy ammonia-rich hailstones dubbed “mushballs” that scientists believe transports ammonia and water in the upper atmosphere and carry them into the depths of Jupiter’s atmosphere. The first signs of lightning on Jupiter were captured in 1979 by Voyager.
Since then, it was thought that Jupiter’s lightning was similar to Earth’s occurring only in thunderstorms where water exists in all of its phases. In the Jovian atmosphere, this would place the storms about 28 to 40 miles below the visible clouds were temperatures around 32-degrees Fahrenheit. However, lightning had been observed as bright spots on the tops of clouds.
The new findings suggest that thunderstorms can throw water-ice crystals high into the planet’s atmosphere, over 16 miles above Jupiter’s water clouds, where they encounter atmospheric ammonia vapor that melts the ice to form a new ammonia-water solution. At those high altitudes, temperatures are below -126-degrees Fahrenheit, which is too cold for liquid water to exist.
The ammonia acts as an antifreeze, lowering the melting point of water-ice and allowing the cloud’s formation with ammonia-water liquid. The falling droplets of ammonia-water liquid collide with the outgoing water-ice crystals electrify the clouds in the new state, leading to lightning. This was a surprise to researchers because ammonia-water clouds don’t exist on Earth. Researchers also found that there were small pockets of missing ammonia on Jupiter. The team believes that a solid, like a hailstone, might go deeper and take more ammonia.