Abstract
A number of recent observational studies reveal a new paradigm for disk galaxies, one in which layers of warm ionized gas, dust structures and magnetic fields commonly extend to considerable heights (of kpc) above their midplanes. This thick disk has an intricate and largely unknown structure. Its inclusion while modeling large scale dynamical processes in the interstellar medium, such as the interacion of HVC with galactic disks, the Parker instability, and the gas response to the spiral density wave, alters considerably the ``classic'' results obtained in the thin disk picture of galactic disks which was popular in previous studies.
