A fog bow is a similar phenomenon to a rainbow; however, as its name suggests, it appears as a bow in fog rather than rain. Because of the very small size of water droplets that cause fog—smaller than 0.05 millimeters (0.0020 in)—the fog bow has only very weak colors, with a red outer edge and bluish inner edge.

Arnold Schwarzenegger gives a thumbs up as he arrives for the Europe premiere of his new movie 'Terminator: Genisys' in Berlin, Germany, Sunday, June 21, 2015. (AP Photo/Michael Sohn)

View of a damaged bridge at the Iguacu Falls on June 12, 2014, in Foz do Iguacu, Brazil, following the overflowing of the Parana river. In neighbouring Paraguay flooding has forced the evacuation of about 150,000 people in Paraguay's capital city Asuncion, authorities said. (Photo by Norberto Duarte/AFP Photo)

A double rainbow is seen above a woman holding an umbrella and selling snacks along the road in Siaya county, Kenya on May 3, 2020. (Photo by Thomas Mukoya/Reuters)

A rainbow appears as people enjoy a warm afternoon on a tour boat at Niagara Falls in Ontario, Canada on October 21, 2024. (Photo by Mert Alper Dervis/Anadolu via Getty Images)

Cambodian motorcyclists drive near a double rainbow, following the conclusion of a ceasefire deal between Cambodia and Thailand, in Siem Reap, Cambodia, on July 29, 2025. (Photo by Daniel Ceng/Anadolu via Getty Images)

Lucy Blacker from Australia takes to the water at the 40 Foot for a Christmas Day Swim in Ireland on December 25, 2022. (Photo by Alan Betson/The Irish Times)

A rainstorm moves over the Atlantic Ocean after passing through Camden, Maine, at sunset, Tuesday, August 1, 2023. (Photo by Robert F. Bukaty/AP Photo)