Page 51 - AFMAN 15-111, 12 MAR 2019

AFMAN15-111 12 MARCH 2019 51

10.7.1. Precipitation is any form of water particle, whether in a liquid, freezing or frozen state,
that falls from the atmosphere and reaches the ground. Precipitation may be encoded in the
body of the observation with or without a reduction in prevailing visibility.
10.7.1.1. Drizzle (DZ): A form of liquid precipitation characterized by fairly uniform
drops with diameters of less than 0.02-inch (0.5 mm) that are very close together. Drizzle
appears to float while following air currents but unlike fog droplets, it does fall to the
ground. May be encoded with the qualifiers light, moderate, heavy and/or freezing.

10.7.1.2. Rain (RA): A form of liquid precipitation that can be showery or uniform and is
characterized by droplets that are generally larger than 0.02-inch (0.5 mm). Smaller
droplets may occur from stratiform clouds but unlike drizzle, the droplets are widely
separated. May be encoded with the qualifiers light, moderate, heavy, showers,
thunderstorms and/or freezing. Precipitation not occurring at the point of observation but
within 10 statute miles is coded as showers in the vicinity (VCSH).
10.7.1.3. Snow (SN): A form of solid precipitation composed of white or translucent ice
crystals, most of which are complex branch hexagonal forms and often combined into
flakes. May be encoded with the qualifiers light, moderate, heavy, showers, and/or
thunderstorms. Additionally, snow can be qualified as drifting, blowing and in the vicinity
if blowing (VCBLSN).
10.7.1.4. Snow Grains (SG): A form of solid precipitation made up of very small, white,
opaque particles of ice; the frozen equivalent of drizzle. When the grains hit hard ground
they do not bounce or shatter and usually fall in small quantities, mostly from stratus type
clouds and never as showers. May be encoded with the qualifiers light, moderate, and/or
heavy.

10.7.1.5. Ice Crystals (IC): A form of solid precipitation that falls as unbranched ice
crystals in the form of needles, columns or plates. Under certain conditions, can appear
without precipitable overhead cloud cover and is commonly referred to as Diamond Dust.
Is not encoded with any qualifiers when it is the sole form of precipitation in the weather
group.
10.7.1.6. Ice Pellets (PL): Hard grains of ice consisting of frozen raindrops, or largely
melted and refrozen snowflakes. Ice pellets are transparent or translucent pellets of ice,
which are round or irregular, rarely conical, and which have a diameter of 0.2 inch (5 mm),
or less.

10.7.1.7. Hail (GR): Precipitation in the form of small balls or other pieces of ice falling
separately or frozen together in irregular lumps. Hail includes small hail, which is pellets
of snow encased in a thin layer of ice which have formed from the freezing, either of
droplets intercepted by the pellets, or of water resulting from the partial melting of the
pellets.
10.7.1.8. Snow Pellets (GS): A form of solid precipitation composed of white, opaque
grains of ice. GS is normally round or conical, brittle, easily crushed, and rebound when
falling on hard surfaces. Diameters range from 0.08 to 0.2 inch (2 to 5 mm).