Definition
Liquid water that remains in the liquid state at temperatures below 0°C (32°F). It is unstable, and when it strikes an aircraft surface or any solid object, it freezes on contact, forming structural ice.
Plain English
Water droplets in the air that are colder than freezing but have not turned to ice yet. The moment they hit something solid, like a wing, they freeze instantly.
Context Anchor
Seen in aircraft icing discussions, especially clear ice, when cold cloud or rain droplets hit the wings, windshield, or other outside parts of the aircraft.
Derivation
Super' comes from Latin meaning 'above' or 'beyond.' Here it means 'beyond the normal limit' — the water is cooled beyond the temperature at which it would normally freeze, yet remains liquid.
Why Pilots Care
Supercooled water droplets freeze instantly on contact with an aircraft, leading to rapid ice accumulation that can disrupt airflow and add weight.
Grounding Statement
Picture flying through a cloud at -5°C. The cloud looks like any other, but the droplets inside are liquid water held below freezing. The instant they contact the wing, they freeze and stick.
Intuition Check
Super cooled water does not mean water that is already ice. It means water that is below freezing but still liquid.
Example Sentence 1
The pilot avoided the cloud layer at 8,000 feet because the temperature and visible moisture suggested supercooled water and a high risk of clear ice.
Example Sentence 2
Recognizing super cooled water in the atmosphere helps pilots anticipate icing hazards during instrument flight.