The Reason Frost Draws Those Feathery Patterns On Your Window Overnight

Nobody paints them, so why do the swirls look identical every winter?

Wake up on a cold morning and the window is covered in delicate ferns and feathers of ice, like the glass sprouted a frozen garden overnight.

This is fern frost, and it forms when water vapor freezes directly onto the cold glass without becoming liquid first. The ice skips right past the water stage.

The feathery branching happens because tiny scratches, dust and streaks on the glass give the ice crystals a place to start, then they grow outward following the moisture.

That's why no two windows ever match, each pattern is a map of that specific pane's imperfections. It's basically your window's fingerprint, drawn in ice.