Application of a diode array spectroradiometer to measuring the spectral scattering properties of cloud types in a laboratory A. R. D. Smedley, A. R. Webb, and C. P. R. Saunders School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Sackville Street Building, Manchester M60 1QD, UK
Abstract. In the last few years diode array spectroradiometers have become useful
complements to traditional scanning instruments when measuring visible and
ultraviolet solar radiation incident on the ground. This study describes the
application of such an instrument to the problem of measuring the radiation
scattered by different cloud-types in a laboratory environment.
Details of how the instrument is incorporated into the experimental set-up
are given together with the development of the system as a whole. The
capability to measure a full spectrum for each scattering angle is an
undoubted advantage, although the limited sensitivity impacts on the
usefulness for optically thin clouds. Nevertheless example results are
presented: (1) scattering phase functions at a range of wavelengths recorded
simultaneously for water clouds, showing spectral deviation at the rainbow
angle and verification of Mie theory; (2) likewise for mixed phase clouds,
with evidence of both halo and rainbow features in a single scattering
function; and, (3) detail of the forward scattering region in a glaciated
cloud showing a barely perceptible halo feature, with implications for the
small-scale structure of the ice crystals produced.
Citation: Smedley, A. R. D., Webb, A. R., and Saunders, C. P. R.: Application of a diode array spectroradiometer to measuring the spectral scattering properties of cloud types in a laboratory, Atmos. Chem. Phys., 7, 5803-5813, doi:10.5194/acp-7-5803-2007, 2007.