multicolored clouds rainbow
© Youtube / Jessielou121
A recent colorful cloud formation over Costa Rica left many residents amazed and terrified, prompting them to speculate whether it was an omen.

A very rare cloud formation with multicolored light was reported earlier this week in the sky over San Jose, Parrita, Pavas, Escazu and Hatillo in Costa Rica.

Pictures and videos of the mysterious clouds immediately went viral on social media sites like Instagram, with the hashtags #EscazuCostaRica and #ElcieloExtraño, loosely translated as "strange sky."

A woman who posted one video of the cloud formation on YouTube said that the cloud over Escazu looked "like the end times", while others suggested that these multi-hued lights are no less than a friendly hello from aliens.

Many were especially surprised to realize that the appearance of the clouds coincided with their country's Independence Day.

"We were just so amazed. We had no idea what it was and we'd never seen anything like it," Joey Petit, a resident who witnessed the clouds with his family, said.

Experts have, meanwhile, described all this as a rare natural phenomenon known as "cloud iridescence."

Comment: More on iridescence:
Its official name is iridescence, although I refer to the phenomenon as "mini rainbows" because large portions of the edges of clouds briefly exhibit many of the colors of the rainbow, in a more muted tone. Today's clouds were shaded pink and blue and teal.

You can "compare this (phenomenon) to a prism," says Stefanie Sullivan, a forecaster at the National Weather Service. "Sunlight passes through the clouds at different wave lengths, bending the light at different angles so you can see the whole spectrum of colors instead of just white."

Eladio Solano, a meteorologist with Costa Rica's National Meteorological Institute, was quoted by the country's news network Teletica as saying that the colorful effect is caused by the sun's light being refracted by water droplets and ice crystals in the cloud.

Interestingly, a similar process led last month to the creation of a "fire rainbow", a cloud formation that took shape in the sky over South Carolina.