The weather in Taipei last week was treacherous and changeable — one minute it was pouring, the next the sun was shining. On Thursday afternoon, a resplendent rainbow appeared over the city.
Due to the high elevation of Chinese Culture University (CCU) on Yangmingshan, Taipei, people on the campus enjoy a broad vista of the city. Chou Kun-hsuan and Liu Ching-hwang, professors of CCU’s Department of Atmospheric Sciences, said that this rainbow was clearly visible from 6:57 am to 3:55 pm on Thursday, meaning that it lasted a full eight hours and 58 minutes. Chou says that this rainbow has broken the six-hour world record observed in the UK in 1994, likely setting a world record for longest-lasting rainbow
Every winter, the northeast monsoon affects northeast Taiwan, and eastern Taipei, exposed to these winds, often has heavy rainfall. As the sun migrates west over the course of the day, it shines down on the eastern part of the city. When a sun’s ray hits an airborne water droplet, the ray will be refracted as it enters the droplet, reflected on the interior wall and then refracted once more as it exits. These two refractions and one reflection are what causes the rainbow.
Chou said that the rainbow in fact consists of four layers — in addition to the more obvious “rainbow” and its outer periphery, referred to as the “secondary rainbow,“ which is fainter than the rainbow itself and with some colors appearing in reverse order, there are also two “supernumerary rainbows” that are less distinct because of their size and location.
Source article: http://www.taipeitimes.com/News/lang/archives/2017/12/06/2003683483