Mount Everest's summit pyramid is the highest obstacle on earth to the wintertime jet-stream winds. Downwind, in its wake, a visible plume can form. The meteorology and composition of the plume are unknown. Accordingly, daily from 1 November 2020 through 31 March 2021 (151 d), we observed real-time images from a geosynchronous meteorological satellite to identify the days plumes formed. The corresponding surface and upper-air meteorological data were collected. The massif was visible on 143 d (95 %), plumes formed on 63 d (44 %) and lasted an average of 12 h. We used the upper-air data with a basic meteorological model to show the plumes formed when sufficiently moist air was drawn into the wake. We conclude the plumes were composed initially of either cloud droplets or ice particles depending on the temperature. The plumes were not composed of resuspended snow. One plume was observed to glaciate downwind. We estimated snowfall from the plumes may be significant.

中文翻译：

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珠穆朗玛峰冬季羽流的形成和组成

珠穆朗玛峰的顶峰金字塔是地球上冬季急流风的最高障碍。顺风，在它的尾迹中，可以形成可见的羽流。羽流的气象学和成分未知。因此，从 2020 年 11 月 1 日到 2021 年 3 月 31 日（151 天），我们每天都会观察来自地球同步气象卫星的实时图像，以确定羽流形成的日期。收集了相应的地面和高空气象数据。该地块在 143 天 (95 %) 可见，羽流在 63 天 (44 %) 形成，平均持续 12 小时。我们使用带有基本气象模型的高空数据来显示当足够潮湿的空气被吸入尾流时形成的羽流。我们得出结论，这些羽流最初由云滴或冰粒组成，具体取决于温度。羽流不是由重新悬浮的雪组成的。观察到一根羽流在顺风处形成冰川。我们估计羽流的降雪量可能很大。