The algorithm for cloud liquid water (CLW) is similar to that for TPW. To measure the wide range of cloud liquid water from thin non-raining stratiform clouds (CLW less than 0.1 mm), to convective clouds with large drops (CLW approaching several millimeters) and even ice, a more complex composite algorithm using different microwave channels is required. CLW, as used here, refers to the amount of liquid water integrated through the depth of the atmosphere.

Several window channels from 23 GHz on the AMSU (19 GHz on SSM/I) to 89 GHz (85 GHz on SSM/I) are needed to account for all these variables and to retrieve accurate amounts. The lower frequencies provide information on the larger drop sizes. As the frequency increases the channels become increasingly sensitive to smaller drops. These channels provide the quantitative information for low rain-rate and non-raining clouds where cloud liquid water is less than 0.3 mm.

The overall quality of the product when compared to radar and aircraft measurements is extremely accurate with an RMS in the neighborhood of 0.05 mm.