Jack Frost making art on your windows. I added a wintery background to a random fractal which resembles ice patterns on a window pane. The glowing blobs of color, elements of the original fractal image, are just a nice plus.
The winter solstice arrives tomorrow.
Click on image for full-size view.
Those patterns on your windows during winter appear as water vapor crystallizes. The patterns are caused by slight changes in the temperature of the air, but other factors, related to the formation of snow and other forms of frozen precipitation, also contribute to variations in design.
They often begin when a film of condensed moisture is frozen by a puff of cold air, and the glass gets a thin sheet of ice. Perhaps another film of moisture forms and trickles down, cutting ditches and tiny streams through the underlying ice, while another puff of cold air freezes this moisture. New frozen vapor molecules may add microscopic ice crystals. The freezing and melting process repeats again and again. Bit by bit the subtle weather conditions etch the window panes with patterns.
Like snowflakes, frost needs a nucleus around which to form. Ice crystals form on dust, small bumps and imperfections in a windowpane, or the texture of plants. Then frost grows as more ice crystals form on the ones that have gotten started. It can make fanciful feathery or spiky patterns.
In contrast, when water vapor condenses into water droplets on a cold windowpane and these droplets then freeze slowly, the ice has a different look, as seen in the close-up photo of frozen condensation droplets. The large bubble-like shapes in the photo are frozen condensation droplets, and the many small lines on their surface are cracks that formed as the ice froze and expanded.