dilnu -dil- gismu

x1 is a cloud/mass of clouds of material x2 in air mass x3 at floor/base elevation x4.

See also carvi, tcima.


In notes:

carvi
x1 rains/showers/[precipitates] to x2 from x3; x1 is precipitation [not limited to 'rain'].
tcima
x1 is weather at place/region x2; (adjective:) x1 is meteorological.
kesydilnu
x1 is a nebula of material x2
mapra
x1 is a quantity of fluff of composition/structure/characterization/substance x2; x1 is fluffy/airy/soft/fuzzy in texture
mardurudra
x1 is a specific kind of bad weather characterized by large dark rain clouds that block out most of the daylight, large, cold rain drops and an overall dark, uncomfortable and unsettling atmosphere, optionally accompanied by icy wind, such that a change in the weather conditions would be a relief to anyone present, both physically and emotionally.