Monday, January 26, 2015

Episode 250 (1-26-15): Reaching the Boiling Point

CLICK HERE to listen to episode audio (3:52)

Transcript, photos, and additional notes follow below.


From the Cumberland Gap to the Atlantic Ocean, this is Virginia Water Radio for the week of January 26, 2015.
This week, we have the second of two special episodes on the physical states of water, written especially for Virginia science students in kindergarten to third grade.

You’re about to hear a mystery water sound.  Have a listen for about 10 seconds, and see if you can guess what this sound is.  And here’s a hint: It’s not only rain that can end up as drops.


If you guessed, ice melting from trees, you’re right!  After a night of freezing rain in January 2015 in Blacksburg, Virginia, thin layers of ice coated many tree limbs.  But energy from the next day’s sunshine soon warmed the ice, causing it to melt from a solid into falling liquid drops.

A day or two later, those liquid drops were gone.  Some of th3 drops sank into the ground or ran off into creeks.  But with more heat from the sun, other drops evaporated, that is, they changed into an invisible gas called water vapor.  You might think you can see water vapor when you look at clouds.  But clouds are actually water in the sky that has cooled enough to condense, or turn back into visible liquid water.

What’s a very common place where can you watch and hear liquid water being turned into a gas and back again?  See if you know while you listen for about 10 seconds to this mystery sound.


If you guessed boiling water on a stove, right again!  A hot stove can add enough energy, fast enough, to liquid water to make it boil and give off bubbles of water vapor.  The escaping water vapor makes the tea kettle whistle, but the steam you can see above a whistling tea kettle is no longer water as a gas.  Instead, its water that cooled as soon as it left the kettle and changed back into a liquid.

The normal temperature of boiling water is 212 degrees Fahrenheit, or 100 degrees Celsius.  But sometimes water boils at a temperature higher or lower than that.  For example, in Denver, Colorado, at about 5000 feet above sea level, water boils at only about 200 degrees Fahrenheit.  How come?  That’s a question for YOU to answer.  And here’s a hint: this sound [SOUND - AIR BEING RELEASED FROM A BIKE TIRE] means somebody’s bicycle tire is losing air pressure.  Good luck!

[The answer to the question, not included in the audio: Water boils when the vapor pressure of the water equals the pressure of the surrounding atmosphere; at that point, bubbles of water vapor escape from the liquid water.  Water reaches atmospheric vapor pressure at 212 degrees F or 100 degrees C when the atmospheric (or air) pressure is at what’s defined as “standard pressure” or “standard sea level pressure,” 29.92 inches of mercury.  At higher elevations, like Denver, air pressure is lower, so water will boil at a lower temperature.  For more details, please see the information sources listed below.]

For other water sounds and music, and for more Virginia water information, visit our Web site at, or call us at (540) 231-5463.  From the Virginia Water Resources Research Center in Blacksburg, I’m Alan Raflo, thanking you for listening, and wishing you health, wisdom, and good water.

[All Internet addresses mentioned were functional as of 1/26/15]

Ice-covered tree in Blacksburg, Va., January 24, 2015
Ice-covered shrub in Blacksburg, Va., January 24, 2015.
Ice pieces fallen from tree limbs in Blacksburg, Va., January 24, 2015.
Water at full boil on a stove in Blacksburg, Va., January 25, 2015.

Sources for this Episode
Virginia Standards of Learning, Virginia Department of Education, online at

“Kindergarten Science Vocabulary,”, online at

“First Grade Science Vocabulary,”, online at

“Second Grade Science Vocabulary,”, online at

“Third Grade Science Vocabulary,”, online at

“Water Properties and Measurements,” U.S. Geological Survey (USGS) Water Science School, online at

“Atmospheric Pressure,” Encyclopedia Britannica, online at

“Boiling Point,” Encyclopedia Britannica, online at

SOLs Information for Virginia Teachers
This episode may help with the following Virginia’s 2010 Science Standards of Learning (SOLs):
Measurements of temperature on metric and English scales (2.1 and 3.1);

Physical properties of matter in different phases (2.3);

Physical properties of water in different phases (K.5);

Energy’s effects on water and water cycle (1.6, 2.3, 3.9)
Weather basics (2.6).

Some Related Virginia Water Radio Episodes on Water’s Physical and Chemical Properties

(Teachers: Please note that the episodes listed below were not written specifically for elementary school children, except for Episode 249, which was written for K-3 students.  The episodes may, however, have information or sounds that might help teachers in various grades with water-related topics.)

Physical phases of water |
EP144 – 1/14/13 (ice on ponds), EP199 – 2/3/14 (snow), EP249 – 1/19/15 (ice on streams)

Surface tension | 
EP217 – 6/9/14

Water as a solvent | 
EP93 – 12/19/11; EP210 – 4/21/14; EP236 – 10/20/14

For a subject index to all previous Virginia Water Radio episodes, please see this link: