A Cost-Effective Tabletop Chamber to Evaluate Cloud Microphysical and Optical Properties
JAKE ZENKER, Christian Pattyn, Lekha Patel, Jeremy Wright, Andres Sanchez, Brian Bentz, Andrew Glen,
Sandia National Laboratories Abstract Number: 466
Working Group: Instrumentation and Methods
AbstractWe have developed a tabletop cloud chamber that can be used to study microphysical and optical properties of cloud droplets generated using different techniques under a wide array of initial conditions. The plexiglass chamber is 15” x 18” x 48”. Droplets can be generated mechanically by dispersing water-solute droplets through a nozzle. Alternatively, mixing clouds can be generated via the injection of a heated humidified flow and desiccated cloud condensation nuclei (CCN) particles. A cooling coil is installed at the base of the chamber which can be used as a coarse control of the temperature inside of the chamber. The temperature and flow rate of the heated humidified air can also be used for fine control of the chamber’s relative humidity and temperature. Further, the humidified flow can be utilized to impose mechanically and thermally generated turbulence.
The chamber is equipped with instrumentation that measures droplet and CCN size distributions, CCN hygroscopicity, and the vertical component of droplet velocity. Additional instruments have been incorporated into the platform to study the bulk optical transmission, scattering, and absorption properties of clouds. The highly modifiable design of the platform promotes the future implementation of additional diagnostic tools.
Experiments have been conducted in the chamber demonstrating droplet growth and evaporation that is consistent with theoretical expectations under different temperatures, relative humidities, and dry aerosol concentrations. Ongoing work is being conducted to rigorously characterize supersaturation conditions in the chamber based on CCN hygroscopicity and initial droplet growth rate.
SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.