Monday, February 12, 2018

Episode 407 (2-12-18): Snow Shows Chemistry and Physics at Work

CLICK HERE to listen to episode audio (4:08).

Transcript of audio, notes on the audio, images, and additional information follow below.

All Web addresses mentioned were functional as of 2-9-18.


From the Cumberland Gap to the Atlantic Ocean, this is Virginia Water Radio for the week of February 12, 2018.  We’re joined this week by guest host Saalehah Habeebah, the spring 2018 intern at the Virginia Water Resources Research Center.

SOUND – ~14 sec

This week, that excerpt from a NOAA Weather Radio advisory for parts of southwestern Virginia on February 3, 2018, opens a freezing-water episode intended especially for Virginia high school science students.  Have a listen for about 40 seconds to a series of mystery sounds, and see if you can guess two basic sciences that are at work when winter turns the landscape white.

SOUNDS - ~40 sec

If you guessed chemistry and physics, you’re right!  You heard a snow shovel, snowmelt salt pellets, and another NOAA Weather Radio excerpt, this time from January 29, 2014, about melting and refreezing potential after an Appalachian snowfall.  The impacts of a snowfall—on transportation, recreation, and water supplies—depend on weather conditions interacting with chemical and physical properties of water and of surfaces and substances in contact with the snow.  One of these properties is snow density, that is, how much water any given snow contains. Snow density determines how much liquid water may result from a given snowpack.  Also, three energy-related properties play key roles in what happens to snow: first, the melting point of water with and without dissolved substances, such as snowmelt salt; second, the light-absorbing and –reflecting capacities of different colors and substances; and third, the capacity of snow and adjacent surfaces to absorb, emit, and conduct heat.  These energy-related properties, combined with snow density, affect how fast the snow will disappear, either by melting or sublimating—that is, turning into vapor without first melting; and whether melted water will evaporate or refreeze onto roadways or sidewalks

Snow chemistry and physics are complicated.   But they affect us in very practical ways, such as the recharge of your water supplies by winter snows; the effectiveness of snow-melting chemicals; and the timing for shoveling a sidewalk to get a dry, clear surface instead of a slippery, refrozen glaze.


For more Virginia water sounds, music, and information, visit us online at, or call us at (540) 231-5463.  Virginia Water Radio is produced by the Virginia Water Resources Research Center, part of Virginia Tech’s College of Natural Resources and Environment.  Thanks to Stewart Scales for his banjo version of Cripple Creek to open and close the show.  In Blacksburg, I’m Alan Raflo, thanking you for listening, and wishing you health, wisdom, and good water.


This Virginia Water Radio episode revises and replaces Episode 199, 2-3-14.

The excerpts from National Weather Service (NWS) winter-weather messages on the mornings of Februrary 3, 2018, and January 29, 2014, were recorded by Virginia Water Radio from broadcasts on those days by NOAA (National Oceanic and Atmospheric Administration) Weather Radio, WXL 60 from the NWS’ Blacksburg, Va., Forecast Office. Information from that office is available online at  Information about NOAA Weather Radio is available online at

Thanks to Kevin McGuire, Virginia Water Resources Research Center, for providing advice and information for this episode.

Click here if you’d like to hear the full version (1 min./11 sec.) of the “Cripple Creek” arrangement/performance by Stewart Scales that opens and closes this episode.  More information about Mr. Scales and the group New Standard, with which Mr. Scales plays, is available online at


A sampler of snow scenes around Blacksburg, Va., on January 17 (top three) and February 4 (bottom two), 2018.



Source: U.S. Geological Survey (USGS), “Water Science School/Snowmelt—The Water Cycle,” online at [bolding added by Virginia Water Radio].

“If you live in Florida or on the French Riviera you might not wake up everyday wondering how melting snow contributes to the water cycle.   But, in the world-wide scheme of the water cycle, runoff from snowmelt is a major component of the global movement of water.  Of course, the importance of snowmelt varies greatly geographically, and in warmer climates it does not directly play a part in water availability.  In the colder climates, though, much of the springtime runoff and streamflow in rivers is attributable to melting snow and ice.

“Mountain snow fields act as natural reservoirs for many western United States water-supply systems, storing precipitation from the cool season, when most precipitation falls and forms snowpacks, until the warm season when most or all snowpacks melt and release water into rivers.  As much as 75 percent of water supplies in the western states are derived from snowmelt.

“During certain times of the year water from snowmelt can be responsible for almost all of the streamflow in a river.  An example is the South Platte River in Colorado and Nebraska. Historically, the South Platte River was essentially ‘turned off’ after the supply of water coming from melting snow was exhausted in late spring.  Today, though, seepage of irrigation water from ditches and fields replenishes the alluvial aquifer (water-bearing deposit of sand and gravel left behind by a river) during spring and summer, and the aquifer slowly drains during fall and winter by discharging groundwater to the South Platte River.   Indirectly, your buying a loaf of wheat bread in the grocery store helps to keep water flowing in the South Platte River all year long.”


Used for Audio

David R. DeWalle and Albert Rango, Principles of Snow Hydrology, Cambridge University Press, Cambridge, United Kingdom, 2008.

Nolan J. Doesken and Arthur Judson, The Snow Booklet: A Guide to the Science, Climatology, and Measurement of Snow in the United States, Colorado State University Department of Atmospheric Science, Fort Collins, Colo., 1997.

James C. Halfpenny and Roy Douglas Ozanne, Winter: An Ecological Handbook, Johnson Publishing Company, Boulder, Colo., 1989.

Ken Libbrecht, Field Guide to Snowflakes, Voyageur Press, St. Paul, Minn., 2006.

Natural Resources Conservation Service and National Water and Climate Center, “Snow Telemetry (SNOTEL) and Snow Course Data and Products," online at  This site provides information on the system of measuring snow pack and its water equivalent in the western United States.

Kimberley Waldron, The Chemistry of Everything, Pearson Prentice Hall, Upper Saddle River, N.J., 2007; see p. 266 for “Why is Salt Used to Melt Ice on Wintry Roads?”

U.S. Geological Survey (USGS), “Water Science School/Snowmelt—The Water Cycle,” online at; and b) “Water Science School/Sublimation—The Water Cycle,” online at

Sources for Snow Measurements in Virginia and Neighboring Areas

Community Collaborative Rain, Hail, and Snow Network (CoCoRaHaS), “Virginia Daily Precipitation Reports,” online at  Following are the main CoCoRaHs links for states neighboring Virginia, plus the District of Columbia:
North Carolina:
West Virginia:

National Weather Service, “Observed Weather Reports”: Blacksburg, Va., Forecast Office, online at; Morristown, Tenn., Forecast Office (serving far southwestern Virginia), online; Baltimore-Washington Forecast Office, online at; and Wakefield, Va., Forecast Office, online at

National Weather Service/Advanced Hydrologic Prediction Service, online at  This site provides maps of precipitation nationwide or by state, with capability to show county boundaries, and archives available for specific days, months, or years.

National Weather Service, “Winter Weather Forecasts,” online at


All Water Radio episodes are listed by category at the Index link above (  See the “Science” subject category for episodes on physical states of water, and the “Weather” subject category for episodes on frost, ice, or snow.

This week’s episode is the fourth in a series in 2018 on freezing water, designed for specific grade levels of Virginia science students. The episodes in the series are as follows:
Episode 403, 1-15-18 – on freezing and ice, for kindergarten through 3rd grade;
Episode 404, 1-22-18 – on ice on ponds and lakes, for 4th grade through 8th grade;
Episode 406, 2-5-18 – on ice on rivers, for middle school;
Episode 407, 2-12-18 – on snow chemistry and physics, for high school.

Another previous episode on snow is Episode 300, 1/25/16, on words for snow in various languages.

Following are links to other previous Water Radio episodes (various topics) designed especially for certain K-12 grade levels:
Episode 250, 1-26-15 – on boiling, for kindergarten through 3rd grade;
Episode 255, 3-2-15 – on density, for 5th and 6th grade;
Episode 282, 9-21-15 – on living vs. non-living, for kindergarten;
Episode 309, 3-28-16 – on temperature regulation in animals, for kindergarten through 12th grade;
Episode 332, 9-12-16 – on dissolved gases, especially dissolved oxygen in aquatic habitats, for 5th grade;


This episode targets the following Virginia 2010 Science SOLs for the Chemistry and Physics courses:

Chemistry Course
CH.5 – phases of matter, kinetic theory, and forces of attraction, including pressure, temperature, and volume principles and laws.

Physics Course
PH.4 – applications of physics to the real word, including roles of science and technology.
PH.7 – energy transfer, transformations, and capacity to do work, including chemical, electromagnetic, mechanical, and thermal energy.

Following are Science SOLs for other grades or courses that may also be supported by this episode:

Grades K-6 Interrelationships in Earth/Space Systems Theme
4.6 – weather conditions, phenomena, and measurements.

Grades K-6 Matter Theme
K.5 – water properties, including flowing, objects floating or sinking, and water occurring in different phases.
2.3 – properties of solids, liquids, and gases.
6.5 – properties and characteristics of water.
6.6 – Properties of air (including pressure, temperature, and humidity) and structure/dynamics of earth’s atmosphere, including weather topics.

Physical Science Course
PS.2 – nature of matter, including elements and compounds, states of matter, physical and chemical properties.
PS.7 – temperature, heat, and thermal energy transfer, including phase changes, melting point, etc.

Earth Science Course
ES.12 – weather and climate.

Biology Course
BIO.2 – water chemistry and its impact on life processes.

Virginia’s SOLs are available from the Virginia Department of Education, online at