The intermittency of turbulence in interstellar clouds: implications for the gas kinetic temperature and decoupling of heavy particles from the gas motions.

Two impacts of the intermittency of turbulence on the physics and chemistry of interstellar clouds are analyzed. Intermittency describes the uneven distribution in space and time of the velocity gradients, shear and vorticity of a flow, resulting in a non-Gaussian distribution of these quantities and of the kinetic energy dissipation rate. One major effect is the generation of locally very hot regions, with kinetic temperatures spanning a broad distribution up to several 10^3^K in atomic HI clouds and sizes of the order of several 10AU. Another effect is an enhancement of the decoupling of the motions of heavy particles from the turbulent gas motions. We show that intermittency by generating very short timescales in the gas motions is most efficient at decoupling the lightest particles (heavy atoms, large molecules and very small grains) which are those which stay well coupled to the gas when a Kolmogorov spectrum is adopted for the turbulence.