EVANSVILLE — If you drove to work Monday morning squinting through a wall of white, you weren’t alone.
Much of the Tri-State awoke to find their surroundings blanketed in a dense layer of fog, diffusing morning sunlight into an orange-yellow glow. Visibility was down enough to prompt the National Weather Service office in Paducah, Ky., to issue an advisory.
Despite the otherworldly visual effect, there was nothing mysterious about the fog itself. As Sunday night gave way to Monday morning, high pressure settled over the Tri-State, bringing with it calm winds and clear skies — perfect conditions for what meteorologists refer to as “radiation fog.”
Without cloud cover to trap heat, the ground radiated warmth back into the atmosphere overnight, causing surface temperatures to drop. As air near the ground neared the dew point — the temperature at which air becomes fully saturated with water vapor — moisture condensed into the suspended water droplets that make up fog.
“What typically happens is we end up with light winds, and when you have light winds and the skies clearing off it sets the stage for temperatures to cool off near the surface,” NWS Senior Forecaster Keith Cooley said. “Basically, you get a cloud at the surface.”
Rising temperatures through mid-morning and southerly winds helped dissipate most of the fog before noon. Weather satellites captured the fog’s formation and subsequent dissipation. Cooley said the imagery illustrated how fog tends to form in low-lying areas near rivers or valleys first.
“You can actually see the outline of the rivers that are in the area,” Cooley said of the images captured by the National Oceanic and Atmospheric Administration’s Geostationary Operational Environmental Satellite.
Looking ahead, NWS forecasts call for unseasonably warm temperatures, with highs in the mid- to upper 60s Monday and Tuesday, climbing to the mid-70s by Wednesday and Thursday, before a cold front bringing the potential for severe thunderstorms moves through Thursday afternoon and evening.
Houston may be contacted at houston.harwood@courierpress.com
This article originally appeared on Evansville Courier & Press: Why Evansville woke up wrapped in dense fog Monday morning
Reporting by Houston Harwood, Evansville Courier & Press / Evansville Courier & Press
USA TODAY Network via Reuters Connect
