We identify 814 discrete H i clouds in 40 dwarf irregular galaxies from the LITTLE THINGS survey using an automated cloud-finding algorithm .
The cloud masses range from \sim 10 ^ { 3 } to 10 ^ { 7 } M _ { \odot } , have a surface density averaged over all of the clouds of \sim 9.65 M _ { \odot } pc ^ { -2 } , and constitute 2-53 % of the total H i mass of the host galaxy .
For individual clouds , the mass including He varies with cloud radius as \log M _ { gas } = ( 2.11 \pm 0.04 ) \times \log R _ { cl } + ( 0.78 \pm 0.08 ) and the internal velocity dispersion varies as \log V _ { disp } = 0.5 \times \log R _ { cl } -0.57 \pm 0.21 .
The H i clouds tend to be in the outer regions of the galaxies , with 72 % of the galaxies having more than 70 % of their clouds outside one disk scale length , and 32 % of the galaxies having more than 50 % of their clouds outside the radius encircling the H ii emission .
36 % of the clouds are essentially non-self-gravitating from H i alone , with a virial parameter that exceeds \alpha _ { vir } \sim 10 , and 5 % have \alpha _ { vir } \leq 2 .
We estimate the missing molecular mass , based on the total star formation rate and a typical molecular consumption time of 2 Gyr , as observed in CO-rich galaxies .
The resulting molecular fraction has a value averaged over the galaxies of 0.23 and correlates with both the surface density of star formation and the fraction of H i clouds in the outer regions .
We conclude that a significant fraction of the inner parts of these dwarf galaxy disks is in the form of dark molecular gas , and that this fraction could be high enough to make the inner disks mildly gravitationally unstable as a precursor to star formation .