自2018年探测器首次记录到这种云以来，科学家一直无法为其存在找到合理的解释。这种云通常被称为阿尔西亚山拉长云（AMEC）。现在终于有了答案。最近，研究人员首次成功模拟了这种云的形成过程，结果表明，它可能由一种从未在任何行星大气中直接观测到的物理过程驱动。
Since it was first recorded by a probe in 2018, scientists have been unable to find a plausible explanation for the existence of this cloud, often referred to as the Arsia Mons Elongated Cloud (AMEC). Until now. Recently, researchers successfully modeled the cloud’s formation for the first time, their results suggesting that it may be driven by a physical process that has never been directly observed in any planet's atmosphere.
巴黎索邦大学行星科学家、该研究的主要作者豪尔赫·埃尔南德斯-贝尔纳尔在新闻稿中表示：“我们发现，必须引入一些奇特的物理学……这些物理学虽然写进了教科书，但被视为理论性的，通常认为不会在自然界中发生。它此前确实从未被观察到实际发生。”“一旦我们在模拟中加入这种物理机制，阿尔西亚山拉长云就如我们所期望的那样出现了。”
"We found that we needed to include some exotic physics … physics that, while included in textbooks, is treated as theoretical and usually thought not to happen in nature. It certainly hasn’t been seen in action before," Jorge Hernández-Bernal, a planetary scientist at Paris’ Sorbonne Université and lead author of the study, said in a press release. "Once we included this physics in our simulations, the AMEC emerged just as we hoped.”
在地球上，云通常是在水蒸气于灰尘或盐粒等微小颗粒的帮助下形成水滴或冰晶时产生的。而这项发表在《自然·地球科学》上的新研究则提出，阿尔西亚山拉长云可能是通过所谓的均质核化形成的，即水蒸气无需任何碎屑帮助，自行直接转变为冰晶。
On Earth, clouds usually form when water vapor creates droplets or ice crystals in the presence of tiny particles, such as dust or salt. The new study, published in Nature Geoscience, instead suggests AMEC could be forming through so-called homogeneous nucleation, where vapor changes directly into ice crystals on its own without any help from debris.
埃尔南德斯-贝尔纳尔解释说：“这类似于凝结的水滴出现在房间中央，而不是窗户上。”“这完全出人意料。”这种现象需要极端条件——10分钟内温度骤降30摄氏度，以及高相对湿度。阿尔西亚山火山也发挥了关键作用。当气流撞上这座高约6.5万英尺的火山时，会产生强大的波，在几分钟内将湿润空气推向大气高处。
“It’s akin to droplets of condensation appearing in the middle of a room, rather than on a window," Hernández-Bernal explained. “It’s wholly unexpected.”This phenomenon requires extreme conditions—a sharp temperature drop of 30 degrees Celsius within 10 minutes and high relative humidity. The Arsia Mons volcano also plays a key role. When wind current hits the 65,000-foot-tall volcano, it creates a powerful wave that launches moist air high in the atmosphere in a matter of minutes.
科学家们曾推测，包括金星甚至地球在内的其他行星的高层大气中也可能发生类似现象，但此前从未被观测到。鉴于该现象所需的极高空气湿度——比地球上测量到的任何数值都要高出10万倍以上——这一结果并不太令人意外。
Scientists have assumed a similar phenomenon could occur in the upper atmospheres of other planets, including Venus and even Earth, but it has never been observed. That’s not too surprising given the extreme air humidity required for this phenomenon, which is more than 100,000 times greater than any value measured on Earth.
在此次建模之前，人们也不知道火星上存在这种湿度的水平。“我们对火星大气的了解远不如对地球大气的了解，因此能在这种程度上重现火星热层夜侧气辉（AMEC）是一个巨大的成功，”埃尔南德斯-贝尔纳尔（Hernández-Bernal）说道，并补充道，“这一结果非常引人注目。”本文最初发表于《连线》杂志捷克与斯洛伐克版，由捷克语翻译而来。
Before this modeling, it was not known that these humidity levels existed on Mars either. “We don’t have nearly as much information about Mars’ atmosphere as we do about Earth's, so reproducing the AMEC to this degree is a big success,” said Hernández-Bernal, adding, “the result is remarkable.”This story originally appeared on WIRED Czech Republic and Slovakia and has been translated from Czech.