Precipitation Types

Regardless of the originating cause, the weather around the world falls into three basic categories of phenomena; precipitation, obscurations and 'other' phenomena. Precipitation is any of the forms of water particles, whether liquid or solid, that fall from the atmosphere and reach the ground. The different types of precipitation are as follows....

Rain

The most commonly observed precipitation, comes either in the form of drops larger than that of drizzle (0.02 inch / 0.5 mm), or smaller drops which, in contrast to drizzle, are widely separated.

Drizzle

Fairly uniform precipitation composed exclusively of fine drops very close together.

Drizzle appears to float while following air currents, although unlike fog droplets, it falls to the ground.

Quite often fog and drizzle occur together.

Ice Pellets
(Sleet)

Precipitation of transparent or translucent pellets of ice, which are round or irregular hard grains of ice consisting of frozen raindrops, or largely melted then refrozen snowflakes.

Hail

Precipitation in the form of small balls or other pieces of ice falling separately or frozen together in irregular lumps.

Associated with thunderstorms, individual hail stone sizes are ¼ inch (5 mm) or greater in diameter.

Hail size 1 inch (2.5 cm) or greater classify a thunderstorm as a severe thunderstorm.

Small Hail
(Snow Pellets)

Precipitation of white, opaque grains of ice. The grains are round or sometimes conical. Diameters are less than ¼ inch (5 mm).

Snow

Precipitation of snow crystals, mostly branched in the form of six-pointed stars.

 Snow

Snow Grains

Precipitation of very small, white, and opaque grains of ice.

Basically, this is frozen drizzle.

Ice Crystals

Generally only occurring in very cold regions, they are falling ice crystals in the form of needles, columns, or plates.

Also called 'diamond dust' this is a type of fog produced by a cirrus cloud on the ground but unlike fog (a stratus cloud on the ground) the individual particles of 'ice crystals' form directly as ice.

The shape of the individual crystals of ice causes the 'light pillar' optical effect above the light source.

Next: Obscurations