The sky was full of dark masses of clouds.

天空中乌云密布。

《牛津词典》

The dark clouds in the sky meant that a storm was coming.

天空中的乌云预示暴风雨即将来临。

《牛津词典》

Suspended on their stilts, the actors remove their masks and reveal their off-white faces, staring terrified at a sunless sky, dark clouds congregating.

演员们被吊在高跷上，他们摘下面具，露出他们苍白的脸，惊恐地盯着没有阳光，乌云聚集在一起的天空。

youdao

Dark clouds filled the sky, as strong winds could be heard whipping against the microphone.

CNN: STORY HIGHLIGHTS

Dark clouds are still present in the sky, however.

FORBES: AAII Investor Update: Investors Optimistic, But Problems Remain

The sky would go gray, with dark clouds building on the horizon.

FORBES: The privacy storm: Facebook capitulates with simplified privacy control settings