Optical and infrared measurements on planetary atmospheres

Imaging, photometric and radiometric techniques are discussed. The ability of these methods to determine atmospheric structure, composition and dynamical features is illustrated. Analysis of Jupiter's backscattered solar radiation shows that the atmosphere in the 100 mb to 5 bar region contains one cloud layer between 3 to 5 bar containing H20 and NH4, and a layer at 400 to 700 mb, consisting of NH3. Polarization and spectral measurements on Venus show that cloud consists mainly (85%) of H2504. Radiometric absorption measurements on Jupiter reveal a warm equatorial belt surrounded by cold zones reflecting the visible banded structure. Planetary heat budgets can be derived from optical radiance measurements. An interferometer spectrometer monitored the thermal effect of a large Martian sandstorm. The Voyager mission used emission spectroscopy to identify and quantify gas constituents in the atmospheres of Jupiter, Saturn and Titan.