On the maintenance of high tropical cirrus

Observations reveal that cirrus clouds are ubiquitous in the tropics and th erefore significantly impact the radiation budget in this region. Here nume rical studies are conducted using a two-dimensional cloud-resolving model w ith explicit microphysics to study the processes that lead to the maintenan ce of tropical cirrus. It is found that despite significant differences in the cloud dynamics among the simulations performed, the model is unable to maintain a cloud against the processes of sedimentation and evaporation und er the assumed environmental conditions. It is hypothesized that a source o f large-scale upward motion must be present to maintain tropical cirrus.