London buses have a cool(凉爽的；酷的) secret. Viewed from above they are often white, not red. This heat-reduction measure, which began in 2004 with the intention of making journeys more comfortable for passengers—particularly those on the top deck—was complete by 2020.(这项降温措施始于2004年，初衷是让乘客的旅途更舒适，尤其是坐在顶层的乘客，到2020年已全面完成。) But buses still struggle to cope with(应对，处理) rising temperatures, and 2025 saw a record(创纪录的；纪录) number of heat-related customer complaints.
伦敦公交车藏着一个清凉的秘密。从高处俯瞰，它们往往是白色的，而不是红色的。这项降温措施始于2004年，初衷是让乘客的旅途更舒适，尤其是坐在顶层的乘客，到2020年已全面完成。但公交车仍难以应对不断攀升的气温，2025年与高温相关的乘客投诉数量创下了纪录。
Part of the answer may be to make them even whiter. A group at University College, London (UCL), led by Ioannis Papakonstantinou, has painted the tops of two buses with material that reflect(反射；反映)s 93% of sunlight. Commercial white paint manages 84%. The difference might sound small, but it takes the new coating over a crucial threshold: the point at which it emits more heat than it absorbs from the sun.(这一差距听起来不大，却让新涂层跨过了一个关键门槛：它排出的热量开始超过从太阳吸收的热量。)
解决办法之一，或许是把它们涂得更白。伦敦大学学院（UCL）一个由扬尼斯·帕帕康斯坦丁努领导的团队，用能反射93%阳光的材料涂刷了两辆公交车的车顶。市售白色涂料只能反射84%。这一差距听起来不大，却让新涂层跨过了一个关键门槛：它排出的热量开始超过从太阳吸收的热量。
Terrestrial objects shed(散失，排出) about 100W per square metre of surface area. The sun heats Earth at ten times that rate. Reflect nine-tenths of incoming solar radiation and the paint breaks even. Reflect more and it can, in principle(理论上，原则上), cool what it is covering down below the temperature of the surrounding air. Since the paint reflects a roughly constant fraction(比例；分数) of sunlight, the advantage is greatest when the sun is strongest.
地球上的物体每平方米表面积大约散失100瓦的热量。而太阳给地球加热的速率是它的十倍。只要反射掉入射太阳辐射的十分之九，涂料就能实现收支平衡。反射得更多，理论上它就能把覆盖的物体冷却到低于周围空气的温度。由于涂料反射阳光的比例大致恒定，太阳越强，这一优势就越明显。
Sunlight sonata
阳光奏鸣曲
Sweating the big stuff
让大物件"出汗"