23 April 2004

The urban heat island effect, snow and pavement

Forrest,

The van I drive into town to go to work has an outside temperature sensor and a readout in the overhead so I see the urban island effect everyday.

One additional thought I had when you discussed soot and snow ["Gypsum Crystals, Soot, Spores and Protozoa in New Mexico Snow," 16 April 2004] is that the roads are quickly cleared of snow, which increases the heat absorbed by the region over the uncleared areas.

One other question. On a clear night would the black roads cool faster than the lighter roads? I am guessing here, but the thermal mass of asphalt might be less than concrete. Something to look into.

Jim Hannon

Readers, what do you think about Jim's question? Editor.

Kudos for The Citizen Scientist

I just visited the new webpage edited by Forrest Mims and it is fantastic! My compliments to you and all involved with it.

Nancy Strack

Hello!!

This is just a quick note of appreciation to Forrest, and all the others who have made the new website possible! It's beautiful! I had 'tuned out' of the SAS updates for a while, but now be assured that I will check in often! All the links are easy to find and load well. And Sheldon, I so very much enjoyed your thorough discussion of field notes. I will soon be traveling to Equador on a college biology adventure, and will be using some of your great tips. Thank you!! Would love to maybe publish findings or something when I return in June. Be well to all, thanks for your dedication.

Jessica Green

The Citizen Science Challenge 1

Hi Forrest,

I read with some interest the pavement challenge ["Announcing Citizen Scientist Challenge 1: Solar Warming of Asphalt Roads," 16 April 2004], and I thought of an idea that I was mulling over to solve a very different problem. Here in the northern Midwest, winters can be quite harsh, and ice on the roadways is a big problem. Most place dump salt on the roadways, which is a mess.

I've always wondered if there is a way to use some of the geothermal energy we have at our disposal. It is my understanding that a couple of meters below the surface of the Earth the temperature is a constantly somewhere between 55-65 degrees Farhenheit. While working at NASA, I came in contact with a device called a heat pipe (see http://www.heatpipe.com/heatpipes.htm). A heat pipe contains fluid (usually water or perhaps a less corrosive fluid) under pressure so that it can be vaporized at the temperatures in which it operates. Heat is applied to the evaporator section, the fluid falls to the condensor section due to buoyancy or even by a wicking agent (like a cotton mesh) and evaporates (and loses heat) at the condensor section. Heat pipes can be up to 15 m long (at least 10 years ago, they could be) and can be used as a structural element.

What I thought would be an interesting idea for melting iced roadways would be to warm the heat pipe with heat from the soil or rock below the road. Conversely, for your problem, the heat pipe would take the heat from the road and carry it into the soil or rock under the road.

Not a solution to your challenge, but an interesting idea.

Brian Mansfield

A note to John Dooley

John,

Your article on measuring sound velocity reminded me of something I have seen and heard recently. It is a relatively new musical instument called a choir chime. This is about the best I can do for a picuture. http://www.malmark.com/choirchimes.html

If you have not seen them they are esentially a square aluminum tube that has been slit to act like a tuning fork. There is a pivoted clapper on the outside and the handle is a tuned cavity that resonates with the tuning fork part. This gives it a nice loud pure tone.

I had a thought of making some to use for a wind chime.

Jim Hannon