Js. Rimmer et Cpr. Saunders, RADIATIVE SCATTERING BY ARTIFICIALLY PRODUCED CLOUDS OF HEXAGONAL PLATE ICE CRYSTALS, Atmospheric research, 45(2), 1997, pp. 153-164
We have artificially produced ice and mixed phase clouds in a laborato
ry cold room using a novel nucleation method applied to a cloud of sup
ercooled water droplets. The number density and size distribution of t
he ice particles have been monitored using a modified PMS 2D probe and
the angular scattering behaviour has been studied. Hexagonal plates w
ith maximum dimensions up to similar to 100 mu m have been produced. W
e find evidence that the appearance of haloes in the phase function is
dependent on there being no, or very few, residual small water drople
ts in the ice cloud rather than on the size of the crystals. The angul
ar scattering behaviour of the mixed phase cloud is dominated by water
droplets in the forward scattering regime. Negative values of the deg
ree of polarisation in the forward scattering direction are associated
with the presence of ice crystals. We find poor agreement between exp
erimental and theoretical phase functions and also find the use of an
effective size parameter to be of little value. (C) 1997 Elsevier Scie
nce B.V.