title: Holographic measurements of inhomogeneous cloud mixing at the centimeter scale.
abstract: Optical properties and precipitation efficiency of atmospheric clouds are largely determined by turbulent mixing with their environment. When cloud liquid water is reduced upon mixing, droplets may evaporate uniformly across the population or, in the other extreme, a subset of droplets may evaporate completely, leaving the remaining drops unaffected. Here, we use airborne holographic imaging to visualize the spatial structure and droplet size distribution at the smallest turbulent scales, thereby observing their response to entrainment and mixing with clear air. The measurements reveal that turbulent clouds are inhomogeneous, with sharp transitions between cloud and clear air properties persisting to dissipative scales (<1 centimeter). The local droplet size distribution fluctuates strongly in number density but with a nearly unchanging mean droplet diameter.
authors.affiliation: Atmospheric Sciences Program, Michigan Technological University, Houghton, MI 49931, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Beals
authors.affiliation: Institute for Atmospheric Physics, Johannes Gutenberg University Mainz, 55128 Mainz, Germany. Aerosol and Cloud Physics Group, Max Planck Institute for Chemistry, 55128 Mainz, Germany.
authors.forename: Jacob P
authors.initials: JP
authors.lastname: Fugal
authors.affiliation: Atmospheric Sciences Program, Michigan Technological University, Houghton, MI 49931, USA. Department of Physics, Michigan Technological University, Houghton, MI 49931, USA. rashaw@mtu.edu.
authors.forename: Raymond A
authors.initials: RA
authors.lastname: Shaw
authors.affiliation: Department of Physics, Michigan Technological University, Houghton, MI 49931, USA.
authors.forename: Jiang
authors.initials: J
authors.lastname: Lu
authors.affiliation: National Center for Atmospheric Research, Boulder, CO 80307, USA.
authors.forename: Scott M
authors.initials: SM
authors.lastname: Spuler
authors.affiliation: National Center for Atmospheric Research, Boulder, CO 80307, USA.
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Stith