clouding

from The Century Dictionary.

• noun The appearance of cloudiness; unequal blending or distribution of light and shade or of colors; specifically, a clouded appearance given to silks, ribbons, and yarns in the process of dyeing.
• noun The dulling of varnish, as by dampness or the fumes of sulphur and ammonia.

from the GNU version of the Collaborative International Dictionary of English.

• noun A mottled appearance given to ribbons and silks in the process of dyeing.
• noun A diversity of colors in yarn, recurring at regular intervals.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb Present participle of cloud.
• noun A mottled appearance given to ribbons and silks in the process of dyeing.
• noun A diversity of colours in yarn, recurring at regular intervals.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the process whereby water particles become visible in the sky