Iridescent clouds paint the sky with the colors of the rainbow
A brightly colored cloud was filmed over Bogor, Indonesia, this week, sparking conversations on social media as to its cause. Somewhat rare, the atmospheric phenomenon that causes these rainbow colors is called cloud iridescence.Thin clouds with water droplets that are uniform in size are the most likely place to see iridescence, although it requires the cloud to be in a specific place and the sun to be at a certain angle. As the cloud evolves, the colors change and can quickly disappear.In this case, the pileus cap, a lenticular cloud on top of a thunderstorm's cumulonimbus cloud, provided the consistent droplets required. Iridescence occurs when light diffracts through the water droplets.Photo Gallery: Iridescent CloudsTypically, the colors are muted, though in this case they were vibrant, as shown by this video and another recent video, likely taken of the same storm.Iridescent clouds can be confused with other iridescent phenomena, including nacreous clouds, which occur before or after sunset, or coronae, which surround the sun or moon.Because iridescence typically occurs in the sky near where the sun appears, it can be potentially dangerous to observe unless the sun is blocked from view by an object such as a building or mountain.Similar iridescent clouds have been sighted recently over Malaysia in April 2026, Vietnam in 2024, and Singapore in 2017. They are not a new type of cloud; in fact, they were painted by Edward Wilson in the Antarctic in 1911.
