Anthropogenic cloud
The intermediate layers of the troposphere are the regions with less influence of human activity. This region is far enough from the surface for not being affected by the surface emissions. Additionally, commercial and military flights only cross this region during ascending or descending maneuvers. Moreover, in this region there exist two types of clouds with a large horizontal extension: "Nimbostratus" and "Altostratus", which cannot originate from human activity. Consequently, it is assumed that there are no anthropic clouds of these two "genera". However, what can occur is enhancing existing "Nimbostratus" or "Altostratus" due to the additional water vapor or condensation nuclei emitted by a thermal power plant, for instance.
Cumulus cloud
The species "Cumulus fractus" is ragged in appearance and can form in clear air as a precursor to cumulus humilis and larger cumulus species-types; or it can form in precipitation as the supplementary feature "pannus" (also called scud) which can also include stratus fractus of bad weather. "Cumulus humilis" clouds look like puffy, flattened shapes. "Cumulus mediocris" clouds look similar, except that they have some vertical development. "Cumulus congestus" clouds have a cauliflower-like structure and tower high into the atmosphere, hence their alternate name "towering cumulus". The variety "Cumulus radiatus" forms in radial bands called cloud streets and can comprise any of the four species of cumulus.
Cumulus supplementary features are most commonly seen with the species congestus. "Cumulus virga" clouds are cumulus clouds producing virga (precipitation that evaporates while aloft), and "cumulus praecipitatio" produce precipitation that reaches the Earth's surface. "Cumulus pannus" comprise shredded clouds that normally appear beneath the parent cumulus cloud during precipitation. "Cumulus arcus" clouds have a gust front, and "cumulus tuba" clouds have funnel clouds or tornadoes. "Cumulus pileus" clouds refer to cumulus clouds that have grown so rapidly as to force the formation of pileus over the top of the cloud. "Cumulus velum" clouds have an ice crystal veil over the growing top of the cloud.