Vertical structure of temperature, composition, and clouds.

Much of what we know about the giant planets comes from observations of the conditions in the upper parts of their molecular-hydrogen/helium envelopes. Remote-sounding and in situ observations of the vertical profiles of pressure, temperature, and composition provide constraints on vertical motion, mixing, heat sources, deep composition, and photochemistry. These observations are complemented by observations of vertical cloud structure. [ABSTRACT FROM AUTHOR]