Newswise — Winter Storm Fern swept across a large swath of the southern and eastern United States, delivering not just a wide range of snow accumulation, but also snow types. Experts say one big reason for those differences comes from a meteorological phenomenon — that the same amount of total precipitation can deliver very different amounts of measurable snowfall, depending on the underlying conditions.

Barrett Gutter, a meteorologist at Virginia Tech who teaches classes in weather analysis, weather forecasting, and severe weather, explains that the snow-to-liquid ratio (SLR), or how much moisture is in a snowflake, can be impacted by a number of factors.

“Very dry snow, which often occurs in mountainous terrain and higher latitudes, can have SLR values closer to 20:1 (20″ of snow = 1″ of liquid), while very wet snow, which often occurs in the southeast, can have SLR values closer to 6:1,” he says.

This explains why snow totals in the Rocky Mountains are often much higher than along the east coast ranges. But elevation isn’t the only determining factor.

“Lower temperatures throughout the atmosphere will lead to drier and fluffier snow (higher SLR) since there tends to be less moisture available, while higher temperatures (closer to freezing) will lead to wetter and denser snow.”

Other factors that impact snow-to-liquid ratios include the height in which snowflakes form, moisture content, and wind speed.

This led to record snowfall totals in places like Toronto, which received nearly two feet of accumulation, while the mid-Atlantic got less total snow, but several inches of sleet, which settled into hard-packed ice.

About Gutter
Barrett Gutter is a collegiate assistant professor of meteorology. Gutter teaches a wide variety of courses, including Weather Analysis, Weather Forecasting, Severe Weather, and Radar and Satellite Meteorology. He also leads a two-week storm chase field course during the summer.

Interview
To schedule an interview with Barrett Gutter, contact Noah Frank at nafrank@vt.edu or 805-453-2556.

BYLINE: Melody Warnick

Newswise — Racing through the air at Olympic speeds, athletes at the Winter Olympics in Milan will need more than strength and skill—they’ll need science. In sports like ski jumping, skeleton, and speed skating, aerodynamics can make the difference between getting the gold or going home empty-handed.

And athletes know it. A scandal erupted at the Nordic World Ski Championships recently when Norwegian team coaches illegally enlarged ski jumpers’ suits to enhance aerodynamics, in the hopes the skiers would fly a few extra meters. One former champion called it “doping, just with a different needle.”

Virginia Tech aerodynamics expert Chris Roy explained what athletes are doing to take advantage of the science of aerodynamics. 

Why did Norwegian coaches alter ski jumpers’ suits?

“When trying to fly without propulsion, it comes down to maximizing your lift while minimizing your drag,” Roy said. “One way to do that is by increasing your surface area, which is what the Norwegian coaches were trying to do.”

But that’s not the only way, Roy said. “You can also get higher lift by curving your shape, called camber, or by changing your angle relative to the oncoming wind. Increasing camber or angle both increase lift, but there’s a limit. Too much camber or angle can lead to stall, where lift drops dramatically and drag increases. You don’t want to hit stall during a ski jump.”

For Olympic athletes, how can aerodynamics shave off time?

“Shape is one of the key aspects of aerodynamics,” Roy said. “Low drag requires an aerodynamic shape.”

“That’s why ski jumpers form a V with their skis, turning their body into efficient lift-generating surfaces. A streamlined wing shape can have 10 times less drag than a circular shape of the same thickness,” Roy said.

Aerodynamics shows up in speed skating too, when skaters “draft” behind others. “By skating behind others, you can drastically reduce your aerodynamic drag, in some cases by up to 40 percent, allowing the skaters in the back to significantly reduce their effort.”

How do athletes use engineering research to train for the Winter Olympics? 

“Lots of Winter Olympic sports use wind tunnel testing to improve aerodynamics, equipment, and apparel, including ski jumping, speed skating, bobsled, skeleton, and luge,” Roy explained. “These sports also use computational fluid dynamics to model these effects on the computer.”  

About Roy

Chris Roy is a professor in the Kevin T. Crofton Department of Aerospace and Ocean Engineering at Virginia Tech, where he’s affiliated with the Center for Research and Engineering in Aero/Hydrodynamic Technologies (CREATe). His research expertise centers around computational fluid dynamics, aerodynamics, and the reliability of computer simulations. Read more about him here.

Schedule an interview

To schedule an interview with Chris Roy, contact Mike Allen at mike.allen@vt.edu or 540-400-1700.