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Fall Speed Measurement and High-Resolution Multi-Angle Photography of Hydrometeors in Free Fall
Tim Garrett, Cale Fallgatter, Konstantin Shkurko, and Daniel Howlett
AMT (Atmospheric Measurement Techniques), Vol 5, Iss 11, 2012
Abstract:
We describe here a new instrument for imaging hydrometeors in free fall. The Multi-Angle Snowflake Camera
(MASC) captures high-resolution photographs of hydrometeors from three angles while simultaneously measuring
their fall speed. Based on the stereoscopic photographs captured over the two months of continuous
measurements obtained at a high altitude location within the Wasatch Front in Utah, we derive statistics
for fall speed, hydrometeor size, shape, orientation and aspect ratio. From a selection of the
photographed hydrometeors, an illustration is provided for how the instrument might be used for making
improved microwave scattering calculations. Complex, aggregated snowflake shapes appear to be more strongly
forward scattering, at the expense of reduced back-scatter, than heavily rimed graupel particles of similar size.
Files:
paper (pdf, 9.93 MB)
BibTex (bib, 1 KB)
Links:
project page
live snowflake feed
gallery of selected flakes
Media:
Besides writing the acquisition software for the MASC, we ran microwave scattering calculations
on a few targets using DDSCAT software package. The results are shown in the paper.
PBRT renderer was used to visualize the targets. The images below show the synthetic volumetric
cube targets, where ice is shown as red and air is shwon as blue transparent cubes. From
left to right are fully filled lattice, extruded front frace of alternating materials in 2D and
lattice with materials alternating in 3D.
Since the MASC takes pictures of snowflakes, we are able to compute scattering off real
snowflakes by using the volumes built by extruding the captured image of a snowflake.
The top row of images below shows the targets used for scaterring, while the bottom row
shows the corresponding captured images.
Acknowledgements: The MASC was developed with support from NASA, NSF, the US
Army, and the University of Utah Technology Commercialization Office. We disclose that T. J. G.
and C. F. are co-owners of Fallgatter Technologies which designs, builds and sells the MASC.
In The News
We are extremely fortunate to have our project mentioned in quite a few avenues and the response seems
to have been rather overwhelming. Below are some of the links to the published articles. There seem to be
some international articles as well, which have been omitted from this list.
Unique photography rig captures snowflakes in mid-flight
They say no two snowflakes look the same — well, scientists at the University of Utah
aren't going to take that for granted. They've devised a photography rig that can take
detailed photos and measurements of thousands of snowflakes in a single night. ...
Read More: NBC News
Cameras Capture Falling Snowflakes in 3D
A gadget that can snap photos of individual snowflakes in freefall could lead to more accurate
weather predictions.
Researchers at the University of Utah have developed the Multi Angle Snowflake Camera (MASC),
which uses three high-speed cameras triggered by infrared sensors to shoot flakes as they float
to the ground, with exposures as quick as 1/25000 of a second. The device also measures the
flakes' fall speed, all without touching them, which would disturb the measurements. ...
Read More: LiveScience Yahoo! News Fox News Discovery News
Automatic 3D Snowflake Camera: Find Out For Yourself If No Two Are Alike
A few weeks ago we challenged you to decipher a black and white image full of seemingly random
white blobs. They turned out to be clumps of snowflakes photographed as they fell to the
ground, and the amazing camera that captured those images can now be yours - if you have deep
enough pockets. ...
Read More: Gizmodo Gizmodo Australia
The high tech camera that can snap snowflakes in 3D as they fall
- and could help forecasters better predict blizzards
A high-tech new camera can snap individual snowflakes in three-dimensions as they are in freefall
- and could lead to more accurate weather predictions.
The Multi-Angle Snowflake Camera (MASC), developed by researchers at the University of Utah,
uses three high-speed cameras triggered by infra-red sensors to capture snow flakes as they float by. ...
Read More: Daily Mail
High Speed Cameras Capture Falling Snowflakes in 3D
There's no denying, there's something absolutely mesmerizing about snowflakes. We've all
marveled at photos of snowflakes under the microscope and intricate snow crystals made
in the lab and we've filled in you in on the chemistry behind those beautiful formations,
but scientists at the University of Utah have developed a way to show us snowflakes like
we haven't seen them before: in 3D. ...
Read More: TreeHugger
Falling Snowflakes Captured in 3D
Snowflakes have been something we’ve marveled at for centuries. The idea that no two are exactly
alike, the way that some are good for snowballs and others are not, and the way that they are
formed have always been topics of interest. Now a team at University of Utah, lead by atmospheric
scientist Tim Garret, have created a super high speed camera set that can take 3D images of snowflakes
in mid-air. The Multi-Angle Snowflake Camera (MASC) is triggered by infrared sensors to capture
snowflakes as they fall from the sky and can capture thousands of images each night. ...
Read More: Visual News
The Multi-Angle Snowflake Camera
Tim Garrett, Edward Bair, Cale Fallgatter, Konstantin Shkurko, Robert E. Davis, and Daniel Howlett
ISSW (International Snow Science Workshop), 2012
Abstract:
We introduce a new instrument called the Multi-Angle Snowflake Camera (MASC). The
MASC provides 10 to 40 µm resolution stereoscopic images of individual hydrometeors in freefall, while
simultaneously measuring their fallspeed. Previously, manual photography of hydrometeors required
collection on a flat surface, a process that is somewhat subjective and remarkably finicky due to the
fragile nature of the particles. By contrast, the MASC is fully automated, and uses a sensitive IR trigger so
that no physical contact is necessary. Field measurements at Alta and Mammoth are showing an
extraordinary variety of hydrometeor forms. The MASC has many potential applications. We highlight
three current projects: 1) improving understanding of the size-fallspeed relationships that are used to
characterize precipitation in Doppler radar retrievals and numerical weather prediction models, 2)
identifying weak crystals that form failure layers in avalanches during storms, and 3) using MASC
measurements in conjunction with a scanning terrestrial LiDAR to estimate precipitation rates during storms.
A New Instrument for High-Speed, High Resolution Stereoscopic Photography of Falling Hydrometeors with Simultaneous Measurement of Fallspeed
Tim Garrett, Cale Fallgatter, Konstantin Shkurko, Daniel Howlett, Sandra Yuter, Nate Hardin, and Jennifer Dean
Abstract:
The Fallgatter Technologies Multi-Angle Snowflake Camera (MASC) provides up to 9 micron
resolution stereoscopic photographic images of individual falling hydrometeors along with
their fallspeed. The MASC uses a sensitive IR motion sensor for a trigger and photographs
the particle surface from multiple angles. By comparison, the Joanneum Research 2DVD provides
only 200 micron resolution silhoueLes, making habit identification hard to impossible.
The potential of the MASC is for improved calculations of the relationships between hydrometeor
microwave scattering properties and their microphysical and fallspeed properties. This past
winter, we deployed two MASCs, an FSSP-100, meteorological instrumentation and a vertically
pointing MicroRainRadar to Alta Ski Area near Salt Lake City. This poster shows hydrometeor
statistics and microwave scattering calculations based on the data obtained between February
and April, 2012.
Files: high res poster (pdf, 35.70 MB) low res poster (pdf, 4.89 MB)