Microwave observations by the Juno spacecraft have shown that, contrary to expectations, the concentration of ammonia is still variable down to pressures of tens of bars in Jupiter. We show that during strong storms able to loft water ice into a region located at pressures between 1.1 and 1.5 bar and temperatures between 173 and 188 K, ammonia vapor can dissolve into water ice to form a low‐temperature liquid phase containing about one‐third ammonia and two‐third water. We estimate that, following the process creating hailstorms on Earth, this liquid phase enhances the growth of hail‐like particles that we call mushballs. We develop a simple model to estimate the growth of these mushballs, their fall into Jupiter's deep atmosphere, and their evaporation. We show that they evaporate deeper than the expected water cloud base level, between 5 and 27 bar depending on the assumed abundance of water ice lofted by thunderstorms and on the assumed ventilation coefficient governing heat transport between the atmosphere and the mushball. Because the ammonia is located mostly in the core of the mushballs, it tends to be delivered deeper than water, increasing the efficiency of the process. Further sinking of the condensates is expected due to cold temperature and ammonia‐ and water‐rich downdrafts formed by the evaporation of mushballs. This process can thus potentially account for the measurements of ammonia depletion in Jupiter's deep atmosphere.

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木星的风暴和氨耗竭：I.“蘑菇”的微观物理学

朱诺号航天器的微波观测表明，与预期相反，氨的浓度仍可降低到木星中数十巴的压力。我们表明，在强风暴能够将水冰放到压力在1.1和1.5 bar之间以及温度在173和188 K之间的区域中时，氨蒸气会溶解到水冰中，形成约三分之一的低温液相氨水和三分之二的水。我们估计，在地球上产生冰雹的过程之后，这种液相会增强冰雹状颗粒（我们称为蘑菇）的生长。我们开发了一个简单的模型来估算这些蘑菇的生长，它们落入木星深层大气中以及它们的蒸发量。我们表明，它们蒸发的深度超过了预期的水云基本水平，在5到27巴之间，这取决于雷暴倾泻而来的假定水冰的丰度以及控制大气与蘑菇之间的热传递的假定通风系数。由于氨气大部分位于蘑菇球的核心，因此氨气的输送趋势往往比水更深，从而提高了工艺效率。由于低温以及蘑菇球蒸发形成的富含氨和水的向下气流，预计冷凝水会进一步下沉。因此，该过程可以潜在地解释木星深层大气中氨消耗的测量值。因为氨气大部分位于蘑菇球的核心，所以氨气往往比水更深地输送，从而提高了工艺效率。由于低温以及蘑菇球蒸发形成的富含氨和水的向下气流，预计冷凝水会进一步下沉。因此，该过程可以潜在地解释木星深层大气中氨消耗的测量值。由于氨气大部分位于蘑菇球的核心，因此氨气的输送趋势往往比水更深，从而提高了工艺效率。由于低温以及蘑菇球蒸发形成的富含氨和水的向下气流，预计冷凝水会进一步下沉。因此，该过程可以潜在地解释木星深层大气中氨消耗的测量值。