这团痕迹可能是飞机或火箭飞上高空后留下的航迹云。
A contrail is the visible vapor trail behind airplanes or rockets traveling at high altitudes.
图片中显示出的水库宽度大约为8千米（5英里），一架从上方飞过的飞机在水库两岸之间留下了一条航迹云。
The width of the reservoir illustrated here is approximately 8 kilometers (5 miles); a jet flying over the reservoir left a contrail midway between the shorelines.
对航迹云的现场研究一直是很稀少的。威斯康星大学白水分校的戴维·崔维斯说，我们所了解到的大部分对航迹云的研究都是基于模型研究的。
Field studies of contrails are rare, says David Travis of the University of Wisconsin-Whitewater. Most of our understanding of their effects is based on model studies.
划过海洋云层明亮的黄色弧线是船舶的航迹——那是些由水蒸汽与船舶排放出来的无数污染微粒凝结而成的云。
The bright yellow arcs that streak the marine cloud layer are ship tracks—clouds that form when water vapor condenses onto the myriad tiny pollution particles in ship exhaust.
由于这些水分分散在更多的颗粒中，在船舶航迹中形成的云滴比典型的海洋层云滴要来的小。
Because the available water is spread among more particles, the cloud droplets that form in the ships' wakes are smaller than typical Marine layer cloud droplets.
由于这些水分分散在更多的颗粒中，在船舶航迹中形成的云滴比典型的海洋层云滴要来的小。
Because the available water is spread among more particles, the cloud droplets that form in the ships' wakes are smaller than typical Marine layer cloud droplets.
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