The warm and dense Galaxy - tracing the formation of dense cloud
  structures out to the Galactic Center
  The past two decades have seen extensive surveys of the far-infrared to
submillimeter continuum emission in the plane of our Galaxy. We line out
prospects for the coming decade for corresponding molecular and atomic line
surveys which are needed to fully understand the formation of the dense
structures that give birth to clusters and stars out of the diffuse
interstellar medium. We propose to work towards Galaxy wide surveys in mid-J CO
lines to trace shocks from colliding clouds, Galaxy-wide surveys for atomic
Carbon lines in order to get a detailed understanding of the relation of atomic
and molecular gas in clouds, and to perform extensive surveys of the structure
of the dense parts of molecular clouds to understand the importance of
filaments/fibers over the full range of Galactic environments and to study how
dense cloud cores are formed from the filaments. This work will require a large
(50m) Single Dish submillimeter telescope equipped with massively multipixel
spectrometer arrays, such as envisaged by the AtLAST project.
