Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Snowflakes falling on cameras

10.04.2013
New device reveals what snow looks like in midair

University of Utah researchers developed a high-speed camera system that spent the past two winters photographing snowflakes in 3-D as they fell – and they don't look much like those perfect-but-rare snowflakes often seen in photos.


This is a collection of snowflakes photographed automatically as they fell at Alta, Utah, by the new Multi-Angle Snowflake Camera developed at the University of Utah.

Credit: Tim Garrett, University of Utah

"Until our device, there was no good instrument for automatically photographing the shapes and sizes of snowflakes in free-fall," says Tim Garrett, an associate professor of atmospheric sciences. "We are photographing these snowflakes completely untouched by any device, as they exist naturally in the air."

Snowflakes in traditional photographs "tend to be of a particular type that conveniently lies flat on a microscope slide, where a camera can get them perfectly in focus, and the photographer can take the time to get the light exactly right," he says.

"These perfectly symmetric, six-sided snowflakes, while beautiful, are exceedingly rare – perhaps one-in-a-thousand at the most," says Garrett. "Snow is almost never a single, simple crystal. Rather, a snowflake might experience 'riming,' where perhaps millions of water droplets collide with a snowflake and freeze on its surface. This makes a little ice pellet known as 'graupel.' Or snowflakes collide with other snowflakes to make something fluffier, called an aggregate. And everything is possible in between."

NASA and the U.S. Army helped fund development of the camera, and the National Science Foundation funded the observations. Garrett says the goal is to improve computer simulations of falling snow and how it interacts with radar. That should help improve the use of radar for weather and snowpack forecasting, and reveal more about how snowy weather can degrade microwave (radar) communications.

"Our instrument is taking the first automated, high-resolution photographs of the complexity of snowflakes while measuring how fast they fall, and is collecting vast amounts of data that can be used to come up with more accurate and more representative characterizations of snow in clouds," Garrett says.

Triple Camera Catches Snowflakes in Air

With help from the University of Utah's Technology Commercialization Office, Garrett and Cale Fallgatter – a 2008 master's graduate in mechanical engineering – formed a spinoff company, Fallgatter Technologies, to make the new camera system, known as the MASC, for Multi-Angle Snowflake Camera, for which a patent is pending.

The device – under development for three years – includes three, industrial-grade, high-speed cameras: two 1.2-megapixel cameras and a 5-megapixel camera, plus two sets of two motion sensors to measure the speed of falling snowflakes. The 5-megapixel camera helps zoom in on single flakes, Fallgatter says.

The Multi-Angle Snowflake Camera has a ring-shaped housing measuring about 1 foot wide and roughly 4 inches tall. The three cameras are mounted on one side, each separated by 36 degrees and pointed toward the center.

"For forecasting the weather, fall speed is the thing that matters," Garrett says. "The weather models right now do OK at simulating clouds, but they are struggling to accurately reproduce precipitation: rain or snow, but particularly snow. The problem is that we do not have a very good sense for how the sizes and shapes of snow particles relate to how fast they fall. This is important because the lifetime of a storm, and where exactly it snows, depends greatly on how fast snow precipitates."

Fallgatter says the multi-angle camera takes only black-and-white images because that gets more information; color filters block some light from images. The snowflake camera also has an extremely fast exposure time of up to one-40,000th of a second so it can capture pictures of fast-moving snowflakes in free-fall without blurring them.

Why Care about Snowflakes?

"Snowflakes are beautiful and fascinating, and truly no two are alike," Garrett says. "This complexity almost makes them worth studying in their own right. But also, there are very serious practical reasons why we need to understand snow better."

Falling snow affects both microwave communications and weather-forecasting radar (which uses microwaves), yet "the big problem is there is a very poor sense of how microwave radiation interacts with complex snowflake shapes," Garrett says.

Weather models used in forecasting now invoke complicated formulas to simulate precipitation – "how cloud droplets turn into snow, snow turns into graupel and all the complicated ways in which particles in a cloud can change in size, shape and fall speed as a storm progresses," Garrett says. "There has been a huge amount of research into improving these formulas, but their accuracy is limited by how well we are able to measure snow and how fast it falls."

He says errors in snowflake shape and size lead to errors in forecasting snowfall amounts and locations.

Garrett says today's weather forecasts still use snowflake research done meticulously by hand in the 1970s in the Pacific Northwest's Cascade Range. Snowflake fall speed was measured, and the flakes then were collected on plastic wrap, photographed, and melted to determine their mass.

"These early researchers got only a few hundred images over two years because they had to collect each snowflake individually by hand," Garrett says. "Our snowflake camera can automatically collect thousands of snowflake photographs in a single night."

Fallgatter and Garrett use two of the multi-angle cameras at Utah's Alta Ski Area, in the Wasatch Range above Salt Lake City. One is located at an elevation of 10,000 feet in Collins Gulch, and the other at 8,500 feet at Alta Base.

"We can look at how the snowflakes change as they fall down the mountainside – if there is a change in the sizes and shapes of snowflakes as they fall," Garrett says. "This is one of the things weather models try to simulate."

The researchers use automatic, image-analysis software to characterize snowflakes by shape, complexity, size and estimated mass.

"The complexity is so vast as to almost defy an easy categorization of snowflakes," Garrett says. "Everything lies along a continuum of possible sizes, shapes and extent of riming."

Also at Alta Base, researcher Sandra Yuter of North Carolina State University operates a vertically pointing radar that measures the precipitation structure in the air column over Collins Gulch.

"The radar tells you how strong the storm is, where and when there are layers of rain and snow, and how tall the storm is," Garrett says. "To interpret what we're seeing with the cameras, it helps to know the structure within the storm and how it is changing with time."

"Ultimately, the primary diagnostic tool that weather forecasters use during a storm is radar, and they want to be able to relate what they see on radar to whether or not there is snow or graupel, and how much."

The Alta Ski Area helps the project by providing a cabin for the instruments, and a Snowflake Showcase through its website, where the public can see a live feed of Multi-Angle Snowflake Camera pictures. Daniel Howlett, an avalanche specialist with the Alta Ski Patrol, helps with camera installation, maintenance and data collection. Software for the snowflake camera was developed by Konstantin Shkurko, a University of Utah doctoral student in computer science.

A University of Utah online gallery of snowflake photographs may be viewed at: http://www.inscc.utah.edu/~tgarrett/Snowflakes/Gallery/

Alta Ski Area's real-time showcase of University of Utah snowflake photos: http://www.alta.com/pages/snowflakeshowcase.php

Fallgatter Technologies: http://www.fall-tech.com

University of Utah Communications
201 Presidents Circle, Room 308
Salt Lake City, Utah 84112-9017
801-581-6773 fax: 801-585-3350
http://www.unews.utah.edu

Lee J. Siegel | EurekAlert!
Further information:
http://www.utah.edu

More articles from Power and Electrical Engineering:

nachricht Did you know that the wrapping of Easter eggs benefits from specialty light sources?
13.04.2017 | Heraeus Noblelight GmbH

nachricht To e-, or not to e-, the question for the exotic 'Si-III' phase of silicon
05.04.2017 | Carnegie Institution for Science

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

NASA's Fermi catches gamma-ray flashes from tropical storms

25.04.2017 | Physics and Astronomy

Researchers invent process to make sustainable rubber, plastics

25.04.2017 | Materials Sciences

Transfecting cells gently – the LZH presents a GNOME prototype at the Labvolution 2017

25.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>