Through the winter months ice formations, referred to as ice ferns and ice flowers form on glass.
They are formed by humid air contacting the sub zero glass pane, in this case the windows in the green store on a day when the outside temperature was −30°C.
These icy patterns seem to grow like plants and resemble ferns or flowers, hence their name.
Dust and other matter present on the glass can change the way these formations occur.
In this case droplets of water that had been melted by the sun on the inside of the double glazing the day before. These patterns were then created as the ice formed over night.