Cloud murus cloud and is the result of air feeding into the storm. Supplementary cloud formations detached from the main cloud are known as accessory clouds. The heavier precipitating clouds, nimbostratus, towering cumulus (cumulus congestus), and cumulonimbus typically see the formation in precipitation of the "pannus" feature, low ragged clouds of the genera and species cumulus fractus or stratus fractus. A group of accessory clouds comprise formations that are associated mainly with upward-growing cumuliform and cumulonimbiform clouds of free convection. "Pileus" is a cap cloud that can form over a cumulonimbus or large cumulus cloud, whereas a "velum" feature is a
Cloud newly formed cloud is determined mainly by air mass characteristics such as stability and moisture content. If these characteristics change over time, the genus tends to change accordingly. When this happens, the original genus is called a "mother cloud". If the mother cloud retains much of its original form after the appearance of the new genus, it is termed a "genitus" cloud. One example of this is "stratocumulus cumulogenitus", a stratocumulus cloud formed by the partial spreading of a cumulus type when there is a loss of convective lift. If the mother cloud undergoes a complete change in genus, it