Frost Pattern on My Window

March 05, 2019


March 2019 Viewer's ChoicePhotographer: Charlene Sauls 
Summary Authors: Charlene Sauls; Jim Foster

The photo above showing this incredibly lacy frost pattern was captured looking out a bedroom window from my home in Harrisburg, Pennsylvania. When the temperature falls to about 15 degrees F (-9 C), as it did this mid-winter morning, water vapor will freeze as it comes in contact with cold window glass, provided that the air on the inside is sufficiently moist. Even when the relative humidity inside is normally low (25 percent), if for example, someone had taken a shower during the morning, water vapor coming in contact with the very cold window glass, especially if the windows are poorly insulated, would result in the type of artistic frost pattern observed here. However, for these patterns to occur, there must be impurities, scratches or dust particles on the surface of the glass that served as points of nucleation for the ice growth. Note that the little squares in the background are part of the window screen. Photo taken on February 1, 2019.

Photo Details: NIKON D7100 camera; 18 - 140 mm lens; f/6.3; 1/160 second exposure; ISO 200; 66 mm focal length.