New research has suggested that Hawaii is the best place on Earth to observe the wonderful spectacle of rainbows. These multi-coloured weather phenomena are caused by the reflection, refraction and scattering of light in water droplets that generate a spectrum of light that appears in the sky in the form of a circular arc, and this study claims that Hawaii is the rainbow capital of the world.
Hawaii is perhaps the best place in the world to observe the wonderful phenomenon of rainbows © Michael Warwick / Shutterstock
In his research, The Secrets of the Best Rainbows on Earth, Dr Steven Businger explains that the rainbows found in America are so extraordinary that visitors and locals alike often leave their cars on the side of the road to photograph these brilliant beams of light.
They are often seen in the windblown haze along with the large crests of fast-moving waves crashing near the shore. One reason is that Hawaii is located at ∼ 20°N latitude in a subtropical region that is dominated by a Hadley cell, which causes subsidence and generally clear skies over Hawaii and generates prevailing trade winds from the northeast.
Hawaiian rainbows are known to be stunning © Toshi Sasaki/ Getty Images
Hawai'i's trade wind-dominated climate is characterised by convective thunderstorms with clear skies between showers, and according to research, the distance between showers is sufficient for sunlight to reach the rain below the showers, producing optimal conditions for spotting rainbows.
At night, the warm sea surface creates heat by convective motion from below, while radiation cools the cloud tops, generating more intense downpours in time for breakfast. A critical factor in the production of frequent rainbows is the mountainous character of the Hawaiian Islands. Although each Hawaiian island has its own unique topography and consequent orographic effects, in all cases the mountains produce pronounced shades in the clouds and precipitation that are key to abundant rainbow sightings.
Businger, a meteorologist at the University of Hawaii at Mānoa, says that rainbows in Hawaii appear in songs and legends, on car licence plates, in the names of Hawaiian sports teams and in local shops. The cultural importance of rainbows is reflected in the Hawaiian language, which has many words and phrases to describe the variety of manifestations there, including rainbows that 'stick' to the Earth (uakoko), vertical rainbows (kāhili), barely visible rainbows (punakea) and lunar rainbows ānuenue kau pō).
