Anvil clouds form near the 220 K (~ −55 °C) isotherm, where water vapor radiative cooling rapidly declines. They initially appear as optically thick and precipitating formations but thin and spread out over time due to various dynamical, radiative, and microphysical processes.
Anvil Clouds and Cloud Radiative Effects
Anvil clouds exert both positive and negative Cloud Radiative Effects (CRE) throughout their life cycle. Fresh, optically thick anvils have a negative CRE, while thinner, aged anvils have a positive CRE. The sign and magnitude of the Anvil Cloud Area (ACA) feedback depend on how changes in ACA are distributed across thick and thin clouds, suggesting that preferential reduction in thick anvil coverage may constitute a positive feedback, while a preferential reduction in thin anvil coverage would be a negative feedback.