  We examine the hypothesis that the red near-infrared colors of some L dwarfs
could be explained by a "dust haze" of small particles in their upper
atmospheres. This dust haze would exist in conjunction with the clouds found in
dwarfs with more typical colors. We developed a model which uses Mie theory and
the Hansen particle size distributions to reproduce the extinction due to the
proposed dust haze. We apply our method to 23 young L dwarfs and 23 red field L
dwarfs. We constrain the properties of the dust haze including particle size
distribution and column density using Markov-Chain Monte Carlo methods. We find
that sub-micron range silicate grains reproduce the observed reddening. Current
brown dwarf atmosphere models include large grain (1--100~$\mu m$) dust clouds
but not submicron dust grains. Our results provide a strong proof of concept
and motivate a combination of large and small dust grains in brown dwarf
atmosphere models.
