A Portland police video showing a cup of water freezing into a cloud of vapor before it hits the ground is getting national exposure after appearing on the ABC News Weather Facebook page and the network’s “Good Morning America” Facebook page.

The video shows Lt. Glen McGary, head of the community policing section, heaving a cup full of hot water into the air in the courtyard of the police station at 109 Middle St. The water appears to transform into a cloud that hangs in the air, with only a little landing on the ground.

The segment was shot in slow motion, with the special effects provided by Sgt. Andrew Hutchings.

The phenomenon works because of the bitter cold. Tuesday temperatures broke a 59-year-old record for that date, dropping to 11 degrees below zero.

At the time the officers performed their experiment, about 7:15 a.m., it was minus 8 degrees.

“That was the first time either of us had done it,” McGary said. “We didn’t even have a test run. I was very surprised. It created quite the cloud.”

An explanation of the phenomenon by professors of atmospheric sciences on the website The Why Files says that the rate at which water evaporates depends on the temperature difference between the water and the air, and is more rapid the lower humidity is and the greater the surface area of the water.

When hot water is tossed into the air, it spreads out and the surface of each water droplet starts evaporating, the site says. Droplets that don’t evaporate freeze into ice crystals in mid-air.

The video on the Portland Police Department Facebook page was viewed 417,688 in just two days.

McGary said the department is trying to improve its connection with residents through its Facebook page, “get people to know we’re humans just like everybody else. And we’re really interested in making snow clouds as well.”