The mystery of sun showers

Some just call it a sun shower. Others say the devils are getting married or there’s a hole in the heavens.

You won’t find any of these terms in the American Meteorological Society’s Glossary of Meteorology, but there’s always a place somewhere on this planet where you can stumble upon this magical weather paradox.

“I’m not a fan of the term,” Gary Lackmann, an atmospheric scientist at North Carolina State University, wrote in an email, adding, “Sun showers are really just rain showers that take place with partly cloudy or broken cloud conditions.”

You’ll often spot them when the atmosphere is unstable — which is more likely during the spring and summer in many parts of the world.

In this condition, temperature variations encourage columns of air to move vertically, rising rapidly in some places and sinking in others. In the rising columns, the air cools, condensing moisture within it and allowing clouds and showers to develop. But the air in the sinking columns suppresses clouds, creating areas of clear skies between showers — and the possibility of sun showers.

You won’t see them if the sun is straight overhead. Your chances to catch the magic are greater when the sun is low on the horizon, like the midmorning or the midafternoon. “This is also a good recipe for rainbows,” Lackmann said.

And there are less-common opportunities to see sun showers, too. It can take several minutes for raindrops to fall from their cloud homes in the sky to the Earth’s surface. And in rare instances when a dissipating cloud produces rain, the sun can break through the clouds while the drops are still falling.

“That’s something you see happen in the tropics or when the rain is blowing and pushing the rain out from under the cloud,” Lackmann said.