A peculiar weather event in southern waters was documented Tuesday off North Carolina’s Outer Banks, when the Back Sound generated columns of smoke like a pot of boiling water.

Cape Lookout National Seashore, part of the National Parks System, posted a photo of the occurrence on Facebook, showing smoke on the water in the literal sense.

“It’s smoking!” said the park service’s post. “This phenomenon is known as ‘sea smoke’ and occurs when very cold air temperatures come in over relatively warmer water. Today’s weather conditions are just right to cause the sounds to ‘smoke.’”

Columns of smoke began rising as a mass of cold air from the north brought cold rain, sleet and around 2 inches of snow Tuesday to some coastal counties, reported the National Weather Service.

The phenomenon is “an infrequent occurrence” off the Outer Banks, but conditions were such on Tuesday that smoke stayed atop the Back Sound most of the morning, park service officials told the Charlotte Observer. The Back Sound is a shallow waterway between Harkers Island and the Shackleford Banks.

“Sea Smoke” — also known as frost smoke or arctic sea smoke — is “similar to the steam that appears over a boiling pot of water or a hot bath,” says AccuWeather.com.

“In order for sea smoke to occur, the air has to be very cold and the water has to be comparatively warm. As a light wind of cold air sweeps in, it cools the warm air immediately above the water … (and the air) condenses into fog, or sea smoke,” says AccuWeather.