The Structure of Molecular Clouds: III - A link between cloud structure
  and star formation mode
  We analyse extinction maps of nearby Giant Molecular Clouds to forge a link
between driving processes of turbulence and modes of star formation. Our
investigation focuses on cloud structure in the column density range above the
self shielding threshold of 1mag Av and below the star formation threshold --
the regime in which turbulence is expected to dominate. We identify clouds with
shallow mass distributions as cluster forming. Clouds that form stars in a less
clustered or isolated mode show a steeper mass distribution. Structure
functions prove inadequate to distinguish between clouds of different star
formation mode. They may, however, suggest that the turbulence in the average
cloud is governed by solenoidal forcing. The same is found using the
Delta-variance analysis which also indicates that clouds with a clustered mode
of star formation show an enhanced component of compressive driving in the
turbulent field. Thus, while star formation occurs in each cloud, independent
of the turbulent driving mechanism, compressive forcing appears to be
associated with the formation of stellar clusters.
