Meanings

cirrus (cloud)

thundercloud

white clouds

cirrocumulus

twilight clouds

speck of cloud

dark nebula

(metaphorically) floating with the tide

contrail

thin clouds

radioactive cloud

wall of clouds

Chinese milk vetch (Astragalus sinicus)

dense clouds

drifting cloud

blue sky

the nebular hypothesis

diffuse nebula

cirrocumulus cloud

cloud of suspicion