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This is Scientific American — 60-Second Science. I'm Julia Rosen.
When lightning sparks across the sky, it sends out low-frequency radio waves that researchers can use to determine its location. Recently, scientists were looking over a map of lightning activity, when they noticed something strange: narrow lines of increased lightning frequency stretching across the Indian Ocean and the South China Sea. Straight features like these are rare on a spherical, spinning planet, except where humans are up to something. In this case, sending ships across the sea.
"Yeah, I had pretty immediately in my mind postulated that this was a result of the pollution from ship exhaust influencing the way the storms develop."
Joel Thornton, an atmospheric chemist at the University of Washington.
"That hypothesis had already been put out generally in the field more than a decade ago. But we had been lacking clear evidence that this was happening on a large-scale, long-time horizon."
The new maps changed that. Thornton and his team found that, on average, lightning activity almost doubled over shipping lanes compared to adjacent areas of the ocean.
The researchers ruled out natural explanations for the pattern, and concluded it must be related to ship exhaust. Exhaust increases the number of tiny particles in the air, on which water vapor condenses to form cloud droplets. Spreading the same amount of water over more particles leads to smaller droplets, which get lifted by updrafts until they reach altitudes cold enough for them to freeze. For reasons scientists still don't fully understand, interactions between these ice particles and water droplets inside the cloud builds up electrical charges—and produce lightning.

Thornton says the ship tracks provide a unique opportunity to isolate the effects of pollution from all the other factors normally at play in storms.
"From a science standpoint it's exciting that we have this ongoing experiment where we know roughly how much particle pollution is being put into the atmosphere, we have a good signature that it's influencing the nature of storms, and then we can use this experiment as a way to improve our understanding of how pollution affects the development of storms and their intensity."
The research was published in the journal Geophysical Research Letters.
The International Maritime Organization recently adopted a rule that will force ships to start using fuels with lower sulfur content. That change will help reduce particle pollution—and should provide Thornton with new data.
"So, if they all do it at the same time in 2020, or even if they stagger it in over the period of a few years, the lightning response should be essentially immediate."
The cleaner fuel standards will help the environment, and boost lightning science, too.
Thanks for listening for Scientific American — 60-Second Science. I'm Julia Rosen.

参考译文

这里是科学美国人——60秒科学Lg]sdyvbZm674*MVz。我是朱莉娅·罗森d#*Y.OtzyeyBF1。
闪电划过天空之时，会释放出低频无线电波，研究人员可利用这种电波确定闪电的位置fQeNS&#gwu%N_JuP。最近，科学家在查看闪电活动图时注意到了一些奇怪的事情：印度洋和中国南海上空闪电频率增加的区域呈细线状.OQ|u-Ij5%OKC。这些线型特征在球形旋转星球上非常罕见，除非人类在那里做了什么f1T==8.I*D0qI。具体来说，这种情况是因为人类在海上航行T8lfC][tLJtnz+g。
“对，我立刻想到了船舶废气污染影响了风暴发展这一假设;7.pie*.jy@ES~Xy8Pk。”
华盛顿大学的大气化学家乔尔·桑顿是说到sO)p@k&*-PfDyrlzJ。
“这种设想在十多年前就在该领域被广泛提出k^F__3xdlyGcm。但是，我们一直缺乏明确的证据，证明这种情况在大规模且长时间的发生xTesTeW),_&1@C0t,Tt。”
而新地图改变了这种状况k((v#CMIcl&。桑顿和团队发现，平均而言，船线上空闪电活动的频率几乎是其邻近海域的两倍D(S0D_I|2RV|KkwX。
研究人员排除了对这种现象的自然解释，然后推断出这一定与船舶废气有关IV~EI9BoIx|Z|ftw[CB。废气使空气中微粒的数量增加，而水蒸气则在微粒上凝结成云滴xStHTP8Z]~^D62IXQ&(w。等量的水接触到更多微粒会形成更小的云滴，上升气流送这些云滴不断升高，直到它们遇冷结冰S,NRuj4s2ux。科学家至今尚不能完全理解，为何云中的冰粒子和水滴会相互作用形成电荷，进而产生闪电g.4UXp_1RO。
桑顿表示，船舶尾迹提供了一个难得的机会，让污染效果从作用于风暴的其他常见因素中分离nxJ3i6%P_P8Ga。
“从科学的观点来看，令人兴奋的是，我们有这种持续进行的实验，让我们得以粗略了解有多少微粒污染进入到大气中，这使我们得以清楚了解微粒会影响风暴的特质，然后我们就可以利用这一实验来更好地理解污染如何影响风暴的发展和强度2r!1,RQ2z7ov。”
这项研究结果发表在《地球物理学研究快报》上9MnUYgf3,@MiJz*-&。
国际海事组织最近通过了一项规定，要求船只开始使用含硫量较低的燃料qciMyN2s^]i4ov|7。这种改变将有助于减少微粒污染，而这也应该会为桑顿提供新数据rkT.rUj|Q~faoAY6W。
“所以，如果所有船只在2020年都使用低硫燃料，或即使它们在未来几年内陆续使用，闪电应该也会立即有所反应9HTy@4l7sy^OnGApE。”
更清洁的燃料标准将有助于改善环境，同时促进闪电科学的发展2^*Hm[KL0ZGPCTK[^l。
谢谢大家收听科学美国人——60秒科学-6oJ.EYzAOBqLZItz.J&。我是朱莉娅·罗森GUv|%n0o#EkFFH[H。

译文为可可英语翻译，未经授权请勿转载！

重点讲解

重点讲解：
1. send out 发出(信号、声音、光、热等)；
例句：Much as bats do, robots send out ultrasonic signals.
机器人就像蝙蝠那样地发出超声波讯号Ie@7j@2wL(K。
2. rule out 排除；不予考虑；
例句：She did not rule out a return to the company in the future.
她没有排除将来回到公司的可能性Ch#YWf!#K#[IL。
3. build up （使）积聚；（使）逐渐增加；
例句：Carbon dust and oil build up in large motors and cause them to short-circuit.
碳尘和燃油在大发动机里越积越多，造成了发动机短路KAEF*DZIRWjt@|e。
4. at play 起作用；
例句：But there are also psychological factors at play.
但也有心理因素在起作用Qys@eg(eNcOK3bJ|Uu_。