A rare and breathtakingly beautiful rainbow cloud appeared in the sky over Costa Rica last Tuesday. It was so impressive that some in the Central American country wondered if it could be a sign from God, or a warning that the end of the Earth was drawing near. The towering cloud was crowned with shimmering rainbow colors that kept shifting and changing shape.
The stunning phenomenon is called a “cap cloud,” or a “pileus.” When a storm is building up quickly, a cap cloud can form as the air above the storm rises fast and then condenses into a cloud that looks like a cap perched on top of a lower cloud. This particular pileus had ice crystals inside of it, so light from the sun was refracted when it hit the crystals.
Meteorologists say that instances of cloud iridescence like this are fairly rare and don’t last long. Residents and tourists in Costa Rica were thrilled by the sight and posted lots of videos and photos online.