Cloud Physics - Current Research and Other Activities

A "random sampling" of some of our recent activities:

Our research is sponsored by the United States National Science Foundation, through the Physical and Dynamic Meteorology Program, and by the NASA, through the Earth Science Enterprise.

Recently our group's research on ice nucleation at water surfaces was highlighted in a News and Views article "Water: Ins and outs of ice nucleation" in the December 8, 2005 issue of Nature.

Our group is developing a "turbulent cloud in a box" to study the interactions between particles and turbulent flows.  The chamber is a cube with "woofers" on each corner, and with this setup we can control the rate at which kinetic energy is dissipated by turbulence. We also simultaneously control the particle size distribution. Particle spatial distributions are measured via digital in-line holography (see more below about the HOLODEC instrument based on the same principle).

In collaboration with colleagues at the Institute for Tropospheric Research (IfT) in Leipzig, Germany, we have flow a new instrument for measuring droplet size and spatial distributions.  The instrument was installed on IfT's helicopter-borne ACTOS (Airborne Cloud Turbulence Observation System).  This project provides a unique opportunity to obtain extremely high-resolution, simultaneous turbulence and cloud particle measurements.  Our instrument is the Phase-Doppler Interferometer for Clouds and Turbulence (PICT, see second photograph), developed jointly with Artium Technologies and UC Santa Cruz.

In collaboration with colleagues at Cornell University we have made measurements of droplet clustering in a highly turbulent cloud in a 20-meter-long wind tunnel. Below is a photograph of the phase-Doppler interferometer used for measuring droplet size, speed, and arrival time.  Support from the Max Planck Institute for Dynamics and Self Organization is gratefully acknowledged.

In the laboratory we study the statistical nature of ice nucleation by cooling a water droplet until it freezes, then warming and melting it, and repeating the process hundreds of times.  The work has provided insight into surface crystallization, which is of fundamental interest in nucleation theory, and into evaporation freezing, which is relevant to ice formation in clouds. The photos below show an overview of the apparatus and a close up photo of the water droplet resting on a platinum resistance thermometer.

Our group recently participated in the IDEAS 3 (Instrument Development and Education in Airborne Science, phase 3) field project, held at the Research Aviation Facility of the National Center for Atmospheric Research.  Our digital holographic instrument, dubbed HOLODEC, successfully recorded hundreds of gigabytes of cloud-particle holograms.  A major objective of this work is to quantify the spatial distribution of droplets in turbulent clouds. 

Graduate student Jacob Fugal was awarded a National Science Foundation Graduate Research Fellowship in 2003 (learn more here).  Jacob also has received funding from the Michigan Space Grant Consortium for his work on HOLODEC.

We study the physics and chemistry of clouds by holding single aerosol particles in a quadrupole trap, where its environment can be controlled and its properties determined through light-scattering studies. The photo below shows a typical quadrupole trap setup (droplet injector is above).

In 2000 Prof. Shaw, together with Don Lenschow (NCAR), Hans Verlinde (Penn State), and John Wyngaard (Penn State), organized the Workshop on Fine-Scale Turbulence and Cloud Microphysics, sponsored by the NCAR Geophysical Turbulence Program.  The workshop final report is available online (see workshop link).

Prof. Shaw regularly visits local schools and community organizations to teach about clouds.  The "cloud in a bottle" experiment shown below is a particular favorite for all ages.

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Address questions about this page to Dr. Shaw at rashaw@mtu.edu.