HI column density statistics of the cold neutral medium from absorption
  studies
  Physical properties of the tiny scale structures in the cold neutral medium
(CNM) of galaxies is a long-standing puzzle. Only a few lines of sights in our
Galaxy have been studies with mixed results on the scale-invariant properties
of such structures. Moreover, since these studies measure the variation of
neutral hydrogen optical depth, they do not directly constrain the density
structures. In this letter, we investigate the possibility of measuring the
properties of density and spin temperature structures of the \HI from
absorption studies of \HI. Our calculations show that irrespective of the
thermal properties of the clouds, the scale structure of the \HI column density
can be estimated, whereas, \HI absorption studies alone cannot shed much light
on either the amplitude of the density fluctuations and their temperature
structures. Detailed methodology and calculations with some fiducial examples
are presented.
