Scattering asymmetry factor ﹩g=\langle \mathrm{cos}\,\theta \rangle ﹩ as a function of frequency for different MW dust mixtures. Also shown are observational estimates for g in various regions. The values are from the following sources, as indicated in the figure: Schiminovich et al. (2001), Witt et al. (1982, 1990, 1992, 1997), Murthy & Henry (1995), Hurwitz et al. (1991), Lillie & Witt (1976), Mattila (1970), Gordon et al. (1994), Gibson & Nordsieck (2003), Burgh et al. (2002), and Calzetti et al. (1995).