Officially recognized by Guinness World Records: The world’s longest-lasting rainbow spotted in Taiwan

Text by MOOK Scenic Spots Family, compiled and reported

On November 30, 2017, a rainbow was visible over Yangmingshan for nine hours. This amazing natural spectacle has been certified by the Guinness World Records, surpassing the six-hour record set in Wetherby, Yorkshire, England on March 14, 1994. This is the first time Taiwan has successfully secured a Guinness World Record for a natural science phenomenon, truly a source of pride for Taiwan.

The Department of Atmospheric Sciences at Chinese Culture University released its observation results and successfully applied for the Guinness World Records certification. The occurrence of such a prolonged rainbow required ideal geographic location, terrain, and weather conditions. The formation of a rainbow requires both moisture and sunlight. In late November, when the northeast monsoon is strong, the appropriately paced winds that day brought a continuous supply of moisture from the sea. Coupled with the presence of an inversion layer, a large amount of water droplets condensed and gathered on the hills to the northeast of the university. The subsiding airflow descending from the mountains kept the southern area clear and sunny, allowing sunlight to shine into the raindrops and form the rainbow.

Additionally, the angle between the incoming light into the water droplets and the rainbow we see is 42 degrees. As the time gets closer to noon, the elevation angle of the rainbow relative to the horizon becomes lower, sometimes even falling below the horizon, making it invisible from flat areas. Since the Chinese Culture University is located on an isolated hilltop, when the rainbow dipped below the horizon, it happened to fall within the valley. As a result, people on the campus could still see the rainbow by looking toward the valley, completing this extraordinary nine-hour journey.

The Guinness World Records certification ceremony was held from 9:00 to 9:40 AM on March 17 at the International Conference Hall on the second floor of the Xiaofeng Memorial Building at Chinese Culture University. Distinguished guests included representatives from Chinese Culture University, officials from Guinness World Records, the Director of the Central Weather Bureau, the Director of the Taipei City Government Department of Information and Tourism, and the Director of Yangmingshan National Park.
 

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