He looked at the heavy sky and sighed.

他看着阴沉沉的天空，叹了一口气。

youdao

In the mornings the sky appeared a heavy shade of mottled grey.

清晨，天空看上去是斑驳的深灰色调。

《柯林斯英汉双解大词典》

The sky over the city was overspread with heavy smog.

城市上空罩上了一层浓重的烟雾。

youdao

The past is depicted in sumptuous color, which renders the pleasures of sun, sea, and sky heavy with doom.

NEWYORKER: Bonjour Tristesse

As the sun hung heavy in the sky, we descended into a valley to find four napping lionesses guarded by two fierce males, their wild manes glowing orange, then amber as the sun set.

BBC: The Serengeti in the off-season

July 2009: The sky is gray and heavy with clouds.

CNN: Born in the east, young Germans still forced to head west