  Aims: An all-sky survey of loop- and arc-like intensity enhancements has been
performed in order to investigate the large-scale structure of the diffuse
far-infrared emission. Methods: We used maps made of 60 and 100 micrometer
processed IRAS data (Sky Survey Atlas and dust infrared emission maps) to
identify large-scale structures: loops, arcs or cavities, in the far-infrared
emission in the Galaxy. Distances were attributed to a subsample of loops using
associated objects. Results: We identified 462 far-infrared loops, analyzed
their individual FIR properties and their distribution. This data forms the
Catalogue of Far-Infrared Loops in the Galaxy. We obtained observational
estimates of f_in~30% and f_out~5% for the hot gas volume filling factor of the
inward and outward Galactic neighbourhood of the Solar System. We obtained a
slope of the power law size luminosity function {beta}=1.37 for low Galactic
latitudes in the outer Milky Way. Conclusions: Deviations in the celestial
distribution of far-infrared loops clearly indicate, that violent events
frequently overwrite the structure of the interstellar matter in the inner
Galaxy. Our objects trace out the spiral arm structure of the Galaxy in the
neighbourhood of the Sun and their distribution clearly suggests that there is
an efficient process that can generate loop-like features at high Galactic
latitudes. Power law indices of size luminosity distributions suggest, that the
structure of the ISM is ruled by supernovae and stellar winds at low Galactic
latitudes while it is governed by supersonic turbulence above the Galactic
plane.
