Airmass precipitation
From Glossary of Meteorology
airmass precipitation[edit | edit source]
Any precipitation that can be attributed only to moisture and temperature distribution within an air mass when that air is not, at that location, being influenced by a front or by orographic lifting.
The most common form of airmass precipitation is airmass showers; however, a moist but stable air mass may produce drizzle independent of frontal or orographic influences.