Multi-Angle Snowflake Camera

 

For a live feed of snowflakes from Alta when it’s snowing, please follow this link to the Snowflake Showcase at Alta Ski Area. Otherwise see this gallery. All images on these pages are copyright Tim Garrett, and are freely available for non-commercial or educational purposes. Otherwise, please contact Dr. Garrett.











The Multi-Angle Snowflake Camera (MASC) takes 9 to 37 micron resolution stereographic photographs of hydrometeors, like those shown in sample images here, from three angles (as shown to the left), while simultaneously measuring their fallspeed. The cameras are triggered by a vertically stacked bank of sensitive IR motions sensors designed to filter out slow variations in ambient light. Fallspeed is derived from successive triggers along the fallpath.  The instrument is sensitive to snowflake sizes ranging from 100 micrometers to 10 cm (100,000 micrometers).








The above are some statistics from the first ever day of MASC field measurements in April 2011, taken at 8500’ altitude in the Wasatch Front.


The instrument is robust to cold and weather and runs unattended. Calibration is limited to occasional and straightforward camera alignment and lens focusing using a calibration tool that attaches to the instrument. C and Python executables are available for image and fallspeed acquisition on PC platforms and for creating a live internet feed from the installation site. The executables include lossless (png) image compression to facilitate with data management. Tens of thousands of images might be obtained in a single day. Matlab scripts are available for detailed post-processing.


The Multi-angle Snowflake Cameras was developed in the Department of Atmospheric Sciences at the University of Utah with support from the US Army, NASA, and the National Science Foundation.  It can be purchased through Fallgatter Technologies, a spin-off company from the University of Utah Technology Commercialization Office. First delivery was in September 2011 to the US Army for UCSB avalanche research at Mammoth Mountain with subsequent deliveries in 2013 to the Department of Energy Atmospheric Radiation Measurement program and Vanderbilt University. The MASC is highly modular and can be adapted to user specifications. For example, a single camera MASC with lower camera resolution can be built at lower cost than a high resolution three-camera version. Or a very high resolution (15 microns or better) or higher depth of field version can be built either with higher cost cameras and different lenses.


For more information, please contact Tim Garrett for further information, or see


Garrett, T. J., C. Fallgatter, K. Shkurko, and D. Howlett, 2012: Fallspeed measurement and high-resolution multi-angle photography of hydrometeors in freefall. Atmos. Meas. Tech., 5, 2625-2633, doi:10.5194/amt-5-2625-2012