Field Notes: The Polar Field Services Newsletter

Flakey Science


We showcase the above pictures—snow crystals captured at Summit Station—as further proof that science is a beautiful thing. Researchers on an NSF-funded, collaborative project collect information on polar cloud properties. The team’s information helps to fill gaps in understanding about how, specifically, clouds work in the polar climate system. We contacted Patrick Wright, the scientist currently monitoring the instruments and launching daily atmospheric sampling balloons, to find out why he’d taken the photos.

I am taking these snow crystal photos as part of the ICECAPS campaign at the Mobile Science Facility at Summit. The PIs are Von Walden (University of Idaho), Dave Turner (NOAA/NSSL), and Matt Shupe (CIRES/CU Boulder, NOAA/ESRL). The photos give a visual, qualitative side to the remote sensing measurements that we make. The cloud radar, LiDARs, infrared interferometer, microwave radiometers, and SODAR provide data that allow us to measure cloud heights and thicknesses, vertical motion and turbulence within the cloud, vertical temperature and water vapor profiles, and the phase of cloud particles (ice vs. super-cooled liquid). The snow crystal photos provide a piece of real evidence from the clouds, and should tell the same story: certain crystal structures only form in certain temperature and humidity conditions. The pictures above were taken during an uncommon precipitation event with unusually warm and supersaturated conditions, allowing formation of well-structured plates and stellar dendrites. Many of the crystals were rimed, a condition where water droplets freeze onto a crystal, sometimes completely obscuring the crystal structure. This indicates the presence of super-cooled liquid in a “mixed-phase cloud.”

The snow crystal photos provide a direct link to our remote sensing measurements, so they are a very valuable component of the campaign, in addition to producing beautiful images!

I used a Nikon D50 digital SLR camera, mounted on tube extensions to a microscope objective that looks at a standard microscope stage, lighted from below. We capture snowflakes on a glass slide and try to keep everything cold. The photo “shed” is outside on our back deck, to keep temperatures at ambient outside conditions. Our total magnification is 5.6x.

With a little investment of time and money, it is possible to build a camera setup similar to the one we are using. For more snow photography information, see: http://www.its.caltech.edu/~atomic/snowcrystals/.–Patrick Wright, ICECAPS technician

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