The heat engine of the climate is the atmospheric water cycle. A better knowledge of the relationships between clouds and the atmospheric water vapor is key to improve our understanding of the climate variability and change. Recent advances in space-borne remote sensing provide new opportunities to investigate the clouds-moisture interactions at the global scale. Vertical profiles of water vapor retrieved from the SAPHIR/Megha-Tropiques microwave sounder are used together with collocated cloud types obtained from infrared and visible sensors onboard geostationary satellites. The temporal evolution of water vapor is analyzed conditionally to the occurrence of five cloud types at various meteorologically relevant scales, including diurnal and seasonal scales. We focus on winter and summer seasons over the tropical oceans. The diurnal cycle of water vapor clearly evolves from the bottom to the top of the troposphere and strongly depends on the cloud type, with a modulation according to the season. A probabilitisc approach is then developed to further link moisture profiles according to the cloud type within the atmospheric column. This is a first step of a more general endeavor to improve our understanding of the atmospheric water cycle.