1.   But towards morning heavy clouds spread across.

2.   By midday, heavy clouds had spread across the sky.

3.   Dark heavy clouds were crawling across the sky, blotting out the stars.

4.   Depression settled over her like a heavy black cloud.

5.   During June and July, heavy cloud May at times build up and the weather can become very humid.

6.   Heavy clouds had gathered over the summit of Mont Blanc.

7.   Heavy grey clouds hung low in the sky.

8.   Looking northwards towards the end of the dale, she frowned to see the accumulation of heavy clouds above the moors.

9.   The heavy clouds that had gathered about the summit of Mont Blanc boiled from within.

10.   The plane glided through heavy clouds.