Scientist suggests Hawaii best place on planet to experience rainbows

Hawai's location in the subtropical Pacific means the overall weather pattern is dominated by trade winds, with frequent rain showers and clear skies between the showers.

Honolulu: An atmospheric scientist from the University of Hawai’i at Manoa recently suggested that Hawaii is the best place on Earth to experience the wonder of rainbows, due to its location and climatic factors.

Rainbows are some of the most spectacular optical phenomena in the natural world and Hawai’i has an abundance of them. In the recent publication, a scientist highlights the Hawaiian cultural significance of rainbows and reviews the science of rainbows and the special combination of circumstances that makes Hawaii a haven for rainbows.

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“The cultural importance of rainbows is reflected in the Hawaiian language, which has many words and phrases to describe the variety of manifestations in Hawai,” said author Steven Businger, a professor in the UH Manoa School of Ocean and Earth Science and Technology.

“There are words for Earth-clinging rainbows (uakoko), standing rainbow shafts (kahili), barely visible rainbows (punakea), and moonbows (anuenue kau po), among others. In Hawaiian mythology, the rainbow is a symbol of transformation and a pathway between Earth and Heaven, as it is in many cultures around the world.” Why is Hawai’ the rainbow capital of the world? The essential ingredients for rainbows are, of course, rain and sunlight.

To see a rainbow on flat ground the sun must be within about 40 degrees of the horizon. As the sun rises to higher angles in the sky during the morning, the height of the rainbow diminishes until no rainbow is visible above the horizon. The pattern is reversed as the sun lowers in the afternoon, with rainbows rising in the east and the tallest rainbows just prior to sunset.

Hawai’s location in the subtropical Pacific means the overall weather pattern is dominated by trade winds, with frequent rain showers and clear skies between the showers.

Businger outlines four additional factors affecting the prevalence of rainbows throughout the islands. “At night a warm sea surface heats the atmosphere from below, while radiation to space cools cloud tops, resulting in deeper rain showers in the morning that produce rainbows in time for breakfast,” said Businger.

Another critical factor in producing frequent rainbows is Hawai’s mountains, which cause trade wind flow to be pushed up, forming clouds and producing rainfall. Without mountains, Hawai’i would be a desert with a scant 17 inches annual rainfall.