  The probability distribution functions (PDFs) of the average densities of the
diffuse ionized gas (DIG) and the diffuse atomic gas are close to lognormal,
especially when lines of sight at |b|<5 degree and |b|>5 degree are considered
separately. Our results provide strong support for the existence of a lognormal
density PDF in the diffuse ISM, consistent with a turbulent origin of density
structure in the diffuse gas.
