Jupiter is the 5th planet from the Sun and the largest in the Solar System. It is a gas giant having mass one-thousandth that of the Sun. Latest observations by Juno, which is NASA’s space probe orbiting Jupiter, reveals major particulars regarding Jupiter’s atmosphere. It was previously thought that, on Jupiter, lightning only occurred in thunderstorms, as on Earth where water exists in all three states – ice, liquid, and gas. But latest revelations prove that this lightning occur on the much higher part of Jupiter’s cloud tops where it is too cold for liquid water to exist. How is this possible!!!
Unlike the Earth, lightning in Jupiter is caused by liquid Ammonia. Jupiter has powerful thunderstorms which throw water-ice crystals high up into the atmosphere, over 25 kilometres above the water cloud. There they encounter Ammonia vapours that melt the ice crystals. This results in the formation of Ammonia-water solution. High up these altitudes, liquid Ammonia acts as an ‘antifreeze’ that prevents the water from freezing entirely. A liquid blend of two parts of water and one part of Ammonia collides with upgoing pure water-ice particles. This phenomenon electrifies the clouds and results in “Shallow Lightning”.
Furthermore, the space probes’ Microwave Radiometer instrument discovered that the amount of Ammonia depletes as we go deeper into Jupiter’s atmosphere. The strange mixture of 2/3 water and 1/3 Ammonia forms the basis of Jovian Hailstorms, also known as Mushballs. They are generated in a similar manner as hail is on Earth. It consists of Water-Ammonia mixture which gets coated and covered by a thicker water-ice crust which is moving upwards. Thus Mushballs grow larger as they move up and down the planet’s atmosphere.
Credits: NASA/JPL-Caltech/SwRI/CNRS
Eventually, the Mushballs become so large that the updrafts cannot hold them further. Then they fall deeper into the atmosphere, where they encounter much warmer temperature. The warmer temperature will eventually result in the complete evaporation of this mixture. This action drags Ammonia and water down to deeper levels of the atmosphere. Thus it turns out that Ammonia isn’t actually missing. But it is transported down in disguise, having cloaked itself with water. Thus when the water and Ammonia are in a liquid state, they are invisible to us until they reach a depth where they evaporate.
Such comparisons of different planets’ atmosphere enable us to develop theories of atmospheric dynamics for all the planets in the Solar System.
Reference: NASA
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