2-13. Low clouds have bases below 7

2-13. Low clouds have bases below 7,000 feet. Low clouds consist mostly of water droplets; however, in colder climates, ice crystals may predominate. These clouds can develop into multilevel clouds and go through various phases of cloud formation. Strato is the prefix referring to the low part of the sky. When used as a suffix, stratus describes a spread-out cloud that looks sheetlike or layered. When used by itself, stratus is a complete name, describing a low-level cloud that is usually gray and covers a great portion of the sky. Other low-level clouds are nimbostratus, stratocumulus (Figure 2-7), cumulus (Figure 2-8), and cumulonimbus.