Falling particles (precipitation)
(Section 1.2.1.2)- From clouds: rain, drizzle, snow, snow grains, snow pellets, hail and ice pellets
- From clear air: diamond dust
Precipitation can reach the Earth’s surface or completely evaporate while falling (virga). When the falling particles reach the observer, it is usually easy to identify the type of precipitation. This identification can then assist in identifying the cloud type especially at night.
Hydrometeors consisting of falling particles may occur as fairly uniform precipitation (intermittent or continuous) or as showers. Showers are characterized by their abrupt beginning and end, and by rapid and sometimes strong variation in the precipitation intensity. Drops and solid particles falling in a shower are generally larger than those falling in non-showery precipitation. Showers only fall from convective clouds (Cumulonimbus and Cumulus); uniform (non-showery) precipitation usually falls from stratiform clouds (mainly Altostratus and Nimbostratus). The hydrometeor type can thus be useful for identifying cloud genera, especially at night.
Table 1 shows the cloud genera associated with each falling hydrometeor type.
