原文链接： Large cities may create their own clouds
发表时间：2019年5月28日
作者： Paul Voosen
分类：气候
The Romantic poets may have it right: Life is simply gloomier in the city. Although it’s well-known that concrete-rich cities are often several degrees hotter than the leafy suburbs, scientists have now determined that cities are also capable of prolonging their own cloud cover.
浪漫主义诗人也许是对的：城市中的生活更加忧郁。尽管我们都知道钢筋混凝土的城市总会比植被丰富的郊区要热一些，但是科学家已经确定，城市也同样能够自己延伸其云层覆盖。
By studying satellite imagery of London and Paris, scientists discovered that during the spring and summer, the modern megacities are persistently cloudier in the afternoon and evening, by several percentage points, than nearby rural areas. The result is surprising: Cities’ lack of vegetation also tends to make them dry, which should lead to less water evaporation and cloud formation.
通过研究伦敦和巴黎的卫星图像，科学家发现春夏时节这些现代化大城市在下午和晚上会出现持续性的多云，与周边郊区地区相比高出几个百分点。这个结果令人惊讶：植被缺乏的城市本应加干旱，而导致更少的水分蒸发和云的形成。
Using ground-based observations in London, the researchers suggest the heat retained by buildings into the late afternoon drives turbulence in the air, feeding moisture to the clouds, they report this month in npj Climate and Atmospheric Science. Although the study only documented these prolonged clouds in two European cities, there are reasons to believe a similar phenomenon is common in cities from Mexico City to Łódź, Poland.
在本月出版的《npj气候与大气科学》杂志发表的报告中，通过伦敦的地面观测结果，研究人员认为建筑物留存的热量在傍晚前后会推动空气湍流为云层提供水分。尽管这项研究只记录了两个欧洲城市的云层延伸情况，但我们有理由相信类似的现象从墨西哥城到波兰罗兹都会相当普遍。
