Thanks to our subtropical location — wherein the weather pattern is dominated by tradewinds, with alternating showers and clear skies — beautifully vivid rainbows are plentiful. For help regarding where to look to catch a glimpse before they fade, there’s a new free smart-phone app, RainbowChase, that predicts likely rainbow spots on Oahu, based on the angle of the sun and moisture in the air.

The app was produced by Steven Businger, a University of Hawaii atmospheric science professor, along with a local businessman. Businger penned “The Secrets of the Best Rainbows on Earth,” an article recently published in the Bulletin of the American Meteorological Society.