Precipitation shaft

A precipitation shaft is a weather phenomenon, visible from the ground at large distances from the storm system, as a dark vertical shaft of heavy rain, hail, or snow, generally localized over a relatively small area.

This is different from a virga, which is a shaft of precipitation that evaporates before reaching the ground.

A precipitation shaft is mostly found underneath convective clouds, such as cumulonimbus cloud or cumulus congestus cloud during a downpour storm, as these have well defined vertical drafts (updrafts and downdrafts) needed for heavy precipitation.

However, an advancing nimbostratus cloud could have a diffuse precipitation leading edge, so its shaft may be unclear.

[citation needed] Developing rain shafts often have a fuzzy, bulbous appearance as they descend.