A rare cloud formation on Tuesday amazed people in Costa Rica — they captured and put it on YouTube, where it quickly went on to become an Internet sensation.
The iridescent and multi-colored cloud had at least one person thinking it signaled the end of the world. Of course, it was not a sign of the end times, but rather a phenomenon called cloud iridescence. After a similar event happened in Colorado in 2007, NASA was able to shed some light on the science behind it.
"These clouds are formed of small water droplets of nearly uniform size," says NASA. "When the sun is in the right position and mostly hidden by thick clouds, these thinner clouds significantly diffract sunlight in a nearly coherent manner, with different colors being deflected by different amounts. Therefore, different colors will come to the observer from slightly different directions."
The recent occurrence was visible in the sky over a number of Costa Rican cities, including San Jose, Parrita, Pavas, Escazu and Hatillo.
The cloud formation itself is known as a "pileus" or "cap cloud" formation, and meteorologists say when this cloud formation is present, it suggests that a storm is quickly gaining strength. In this particular case, the cloud included ice crystals, which refracted light from the sun.
The best time to spot these clouds is right before a storm, but they don't tend to last very long, and won't generally be as spectacular as the one recently seen in Costa Rica.
A similarly remarkable cloud was however spotted last month in South Carolina that was dubbed the "Fire Rainbow."
Via: The Washington Post