High-altitude cirrus clouds in the tropics are said to dehumidify the air entering the stratosphere, maintaining the dryness of the stratosphere. Does cirrus formation guarantee dehydration? Can we use observations to find connections between cirrus and water vapor near the tropical tropopause? These are the questions I have become interested in during my PhD track here in Madison. I am also involved in satellite retrievals of ice cloud properties. We seek to utilize the suite of active radar/lidar and passive radiometer observations along the A-Train constellation to characterize ice clouds in as much detail as possible. We are testing which cloud paramters can possibly be retrieved through analyzing the Shannon information content of these observations. Following the analysis, our goal is to develop a joint retrieval algorithm using AIRS, MODIS, CloudSat CPR, and CALIPSO.