Linked from
The 13 pages that link to Supercooling, each with the reason it gives.
Ice crystalRelated: Supercooled cloud droplets can remain liquid until an ice crystal nucleates.
VitrificationRelated: Supercooled liquid is the necessary intermediate state on the way to glass.
SnowRelated: Supercooled droplets provide liquid water that can freeze onto ice crystals.
FreezingRelated: Food water can remain liquid briefly below its freezing point before ice nucleates.
Metastable stateBroader topic: The liquid remains metastable until crystals nucleate.
Ice stormRelated: Freezing rain can remain liquid in subfreezing air until it strikes an object.
GraupelRelated: Cloud droplets can remain liquid below 0°C until they strike a snowflake.
Altostratus cloudRelated: Altostratus can contain supercooled droplets at temperatures below 0 °C.