Definition
Liquid water drops or droplets that remain in liquid form at temperatures below 0°C (32°F). Although the temperature is below freezing, the water has not yet turned to ice. When these drops strike a solid surface — such as an aircraft in flight — they freeze on contact, producing structural icing.
Plain English
Tiny water drops in clouds or rain that are colder than freezing but still liquid. They stay liquid until something disturbs them. The moment they hit your aircraft, they freeze and stick.
Context Anchor
Seen in weather and aircraft icing discussions, especially when flying in visible moisture near or below freezing temperatures.
Derivation
‘Supercooled’ comes from ‘super-’ (Latin, meaning ‘beyond’) and ‘cooled.’ It literally means cooled beyond the normal freezing point without freezing — capturing the unusual fact that the water is colder than 32°F but still in liquid form.
Why Pilots Care
Contact with an aircraft can instantly turn these droplets to ice, causing rapid accumulation that reduces lift and increases drag.
Grounding Statement
Picture a cloud at 20°F filled with liquid water drops just waiting for a surface to freeze onto. Your wing flies through it, and ice forms instantly where the drops hit.
Intuition Check
Supercooled does not mean the water is already ice. It means the water is below freezing but still liquid until something makes it freeze.
Example Sentence 1
The pilot exited the cloud layer promptly after ice began forming on the wing, recognizing the conditions indicated supercooled droplets.
Example Sentence 2
Preflight weather briefing noted supercooled droplets in the clouds, so the crew activated the de-ice boots before entering the area.