Hail
As defined in METARs, hail is 5 mm or more in diameter. It is mainly a mid-latitude phenomenon and is always associated with intense thunderstorms with strong updrafts. Hail is sometimes found in tropical areas, particularly in the Sahel.
Hail affects aviation in various ways.
- Large hailstones can shatter windscreens and damage the skin of an aircraft, affecting its aerodynamics
- Hail can severely damage propeller and engine blades
- Hail can block air inlets or be deposited within air intakes, impacting engine performance
- Hail showers can create an extremely slippery surface on runways and taxiways that can affect a plane's breaking action