Definition
A form of liquid precipitation in which water droplets fall from clouds to the surface, with droplet diameters generally 0.5 mm or larger. Rain forms when cloud droplets grow large enough — through collision and coalescence or through the melting of ice crystals — that rising air can no longer support them.
Plain English
Water falling from clouds as drops big enough to feel and see, rather than as mist, snow, or ice.
Context Anchor
Pilots encounter rain in weather reports, forecasts, in-flight weather, and runway condition decisions.
Why Pilots Care
Rain reduces visibility, can cause hydroplaning on runways, and signals potential convective activity with turbulence or icing.
Grounding Statement
If water drops are falling from clouds and reaching the ground, the aircraft is operating in or near rain.
Intuition Check
Do not think of rain as only a comfort issue or a windshield issue. For pilots, rain is weather that can affect visibility, landing distance, and go/no-go decisions.
Example Sentence 1
The METAR reported light rain and a 700-foot ceiling, so we delayed the VFR departure.
Example Sentence 2
Moderate rain reduced visibility during the approach, so the pilot flew the ILS.