noun
cloud cover; degree of cloudiness
Meteorological term for the fraction of the sky covered by clouds, often expressed in tenths or oktas.
今日の雲量は8で、ほとんど曇り空です。
Today's cloud cover is 8, so it's mostly overcast.
気象観測では、雲量を0から10の11段階で表
In weather observation, cloud cover is expressed on an 11-point scale from 0 to 10.