Examples from literature

• But woolly, white cloud banks sailed lazily aloft, intensifying by contrast the blue of the sky. 
• I don't like the look of that haze and that cloud bank. 
• Light fleeces of cloud drifted in the azure sky, but to the west heavy cloud banks threatened with rain. 
• The farmer considered, casting an anxious glance at the cloud bank into which the sun had sunk. 
• Three gleaming specks had just burst through a cloud bank to the north.