**Moisture interchange between clouds and environment in a tropical atmosphere

In this work, we use data collected during the intensive operation period of TOGA-COARE to study, on a case-by-case basis, the nature of moisture interchange between cloud systems and their environment. For our ten-case sample, we have found a correlation between cloud-top height and mid-level moisture. We also argue that it is mid-level moisture which is controlling the height of the clouds and not vice-versa. Furthermore, by using the stochastic mixing model, Raymond and Blyth (1992), we obtained evidence that entrainment is a plausible mechanism to explain how mid-level moisture exercises such a control.