I stood for a moment gazing at the fell, curving clean and cold into the sullen sky.
I glanced back at the heavy black smoke that rose into the sullen sky.
The sullen sky was darkening to purple as the sun began to set.
Watching eyes were turned toward the sullen sky.
The sullen sky became duskier, and the damp air turned chill.
It wasn't dark across the meadows, despite the sullen sky.
Behind him, angry clouds raced across a sullen sky.
We walked along the deserted beach, searching the sullen sky in vain for a patch of blue.
Smoke rose to the sullen sky and gathered there.
The balloon, released, rose sharply into the sullen gray sky.