cloud point

1. n. [Drilling Fluids]
The temperature at which a solution of a surfactant or glycol starts to form micelles (molecular agglomerates), thus becoming cloudy. This behavior is characteristic of nonionic surfactants, which are often soluble at low temperatures but "cloud out" at some point as the temperature is raised. Glycols demonstrating this behavior are known as "cloud-point glycols" and are used as shale inhibitors. The cloud point is affected by salinity, being generally lower in more saline fluids.
2. n. [Heavy Oil]
The temperature at which wax crystals first start to form in a crude oil. Wax appearance temperature (WAT) and wax precipitation temperature (WPT) are other synonyms.