Frost Crystal

A feathery ice formation that grows overnight on cold surfaces/Weather & Climate

Frost crystals form when water vapor in the air deposits directly as ice on surfaces that have cooled below the frost point (a process called deposition). On cold, calm nights, frost can grow into elaborate feathery or fernlike patterns called 'window frost' or 'fern frost' on glass surfaces. These patterns emerge because ice crystal growth is sensitive to tiny variations in temperature and humidity, causing branches to form at 60-degree angles following the hexagonal molecular structure of ice. A single frost crystal can grow from a few micrometers to several centimeters in a single night, adding new branches every few minutes.