The known components of the atmosphere's water vapor budget are examined, and various scenarios for climatic water vapor feedbacks are presented. Current data shows that in the tropics, humidity distributions above the trade inversion consist in large very dry regions, and comparably sized regions associated with high humidity. The latter are associated with regions of deep convection and cirrus outflow. Most OLR originates in the dry regions, and a possible feedback would consist in changing the areal coverage of the dry regions. Simulated radiance data for such an hypothesized feedback is generated, and current retrieval schemes are examined in order to see whether climatically relevant changes can be discerned in satellite retrievals