Precipitation
Precipitation is any form of water, liquid or solid, that falls from clouds to the ground, including rain, snow, sleet, and hail.
Definition
Precipitation is any form of water, liquid or solid, that falls from clouds to the ground, including rain, snow, sleet, and hail, forming once water vapor condenses on tiny particles in a cloud and the resulting droplets or ice crystals grow large enough to fall, often needing to grow about a million times bigger in volume before gravity wins. Two mechanisms bridge that growth gap: collision-coalescence in warm clouds, and the Bergeron process in cold clouds, where the lower saturation vapor pressure over ice lets ice crystals grow at the expense of supercooled droplets, and precipitation type, rain, snow, sleet, or freezing rain, depends on the temperature profile of the air between cloud base and the ground. Because it depends on vertical moisture flux, orographic lifting, frontal ascent, and convective updrafts all produce the heaviest totals, making precipitation the most spatially variable of all climate variables.
Example
Charlotte receives about $110$ centimeters, roughly $43$ inches, of precipitation in a typical year, mostly rain with a little winter snow, and freezing rain is a Piedmont specialty in which warm air aloft melts snow into rain that then refreezes on contact within a shallow, below-freezing layer trapped against the Appalachians. Hurricane Florence dropped nearly $90$ centimeters of rain on parts of eastern North Carolina in 2018, while the Appalachian escarpment near Mount Mitchell receives over $200$ centimeters a year from orographic lift of moist air, and Great Plains supercells have produced hailstones up to $20$ centimeters across.
Key Insight
Not every cloud produces precipitation, since most of them never grow droplets large enough to fall, and most rain in the mid-latitudes actually starts as snow, with raindrops over Charlotte even in July usually beginning as ice crystals high in the cloud that melt on the way down. Cloud seeding only works where the Bergeron process is the bottleneck, adding ice nuclei that supercooled clouds lack, but it cannot conjure precipitation from a cloud that has no moisture to give in the first place.