Frosty Start

Day 28/365

Panes of glass lose heat quickly on cold nights, cooling the water vapour molecules in the indoor air nearest the glass.

The structure of the elaborate branching depends on both the temperature and humidity of the air, as well as how smooth and clean the glass is. When the air is dry, the water molecules condense slowly out of the air and cluster together in stable hexagons.

Feather-like patterns are more likely to form on clean windows and when the air is heavy with water molecules.