Gibbard S, Levy E H, Lunine J I
Lunar and Planetary Laboratory, University of Arizona, Tucson 85721, USA.
Nature. 1995 Dec 7;378(6557):592-5. doi: 10.1038/378592a0.
Lightning is a familiar feature of storms on the Earth, and has also been seen on Jupiter and inferred indirectly to occur on Venus and Neptune. On Jupiter, lightning may be important as a source of energy to drive chemical reactions in the atmosphere, perhaps determining the abundances of molecules such as CO, HCN and C2H2. Lightning may be generated in Jupiter's water clouds by a mechanism similar to that which operates in terrestrial thunderstorms. Here we investigate the development of lightning by modelling the thunderstorm separation of electrical charge on precipitating ice particles at varying depths in Jupiter's atmosphere. We find that lightning can indeed be generated in the jovian water clouds, and that--in agreement with estimates from the analysis of Voyager images--it is most likely to occur at the 3- or 4-bar pressure level. Our model also predicts that a condensed-water abundance in the range of at least 1-2 g m-3 is required for lightning to occur in jovian thunderstorms--a prediction that may be tested when the Galileo probe arrives at Jupiter on 7 December 1995.
闪电是地球上风暴常见的特征，在木星上也能看到，并且通过间接推断可知金星和海王星上也会出现。在木星上，闪电作为一种能量来源对驱动大气中的化学反应或许很重要，可能决定了诸如一氧化碳、氰化氢和乙炔等分子的丰度。木星水云中的闪电可能是由一种类似于地球上雷暴中起作用的机制产生的。在此，我们通过模拟木星大气中不同深度降水冰粒子上电荷的雷暴分离来研究闪电的形成。我们发现木星水云中确实能够产生闪电，并且——与对旅行者号图像分析的估计结果一致——最有可能发生在3至4巴的压力层。我们的模型还预测，木星雷暴中发生闪电需要凝结水丰度至少在1至2克每立方米的范围内——当伽利略探测器于1995年12月7日抵达木星时，这一预测或许能够得到验证。
