The structure of molecular clouds.

The morphology and dynamics of Galactic molecular clouds are examined, summarizing the results of recent observations. Topics addressed include the overall properties of small (2-pc-diameter, 40-solar-mass) high-Galactic-latitude local clouds (HLCs); the IR features, kinematics, and internal motions of HLCs; the evidence against HLCs being bound by gravity, pressure, or magnetic fields; HLC internal structures; broad high-velocity CO-line wings in HLC spectra; and data suggesting that HLCs were formed by interstellar shocks less than about 1 Myr ago. The giant Rosette Molecular Cloud is then described on the basis of (C-13)O mapping. This cloud has a structure characterized by (1) large (gravity-bound) and small (unbound or pressure-bound) clumps with density proportional to radius and (2) pervasive interclump gas which is optically thick in CO.