MadSci Network: Chemistry |
Nick,
I had a lot of trouble finding any information on this one, but I asked around and here is what I
can gather:
The normal state of affairs is for grains of any solid material to make
noise as they are rubbed against each other. Such is the case for snow
under foot on a *cold* day.
On a mild day the snow is melting, so the snowflakes are coated by a thin,
lubricating layer of liquid water. If the temperature is moderate but
below freezing, the pressure of someone's foot will shift the solid-liquid
equilibrium toward liquid while the pressure is applied, generating that
thin, lubricating layer of liquid water. (The shift is towards the liquid
because the density of liquid water is greater than that of ice at zero
degrees Celsius.)
I found this on the web:
Snow ice is any ice that forms from snow or slush freezing on the top surface. It has a grain structure comprised of the ice granules from the original slush. It contains a lot of air trapped between the ice gains.
Here is the site: http://206.1.7.10/sail/ice/pg35.htm
The National Snow and Ice Data CENTER is another link you might want to look at.
If you don't like or understand this message, feel free to let me know.
-Jeff