空 and 雲: the sky and clouds within it
Separate a space from the visible objects in it when describing the sky.
The sky as a space
空 (そら) means sky. 「空を見上げました」 means looking up at the sky.
「空が暗くなりました」 says the sky became dark. This alone does not identify nightfall or rain clouds as the cause.
The appearance of clouds
雲 (くも) means cloud. 「白い雲が浮かんでいます」 describes white clouds floating in the sky.
「雲の間から日が差しました」 says sunlight shone through gaps between clouds. It does not say all clouds disappeared.
Whole versus part
「空の一部が雲で隠れています」 says part of the sky is hidden by clouds. Do not expand 一部 to the entire sky.
「雲は多いですが、雨は降っていません」 says there are many clouds but no rain is falling. Cloud amount and actual rainfall are separate information.
Do many clouds alone establish that rain is falling now?
Show the answer and why
No. Distinguish cloud conditions from actual precipitation.