Homework #2         Glaciology and the Cryosphere, GEOL 4888,  Spring 2019         Humphrey

 

            A fairly easy homework, especially since we sketched the results in class after doing the experiment, our bottle was about 231 gms, and the plastic weighed about 11gms.   We got about 100 gms of ice.  Double underline your answers so I can find them.

1.    Calculate how much ice is formed in a 200 gm (net) bottle of supper-cooled water at -7C, if the bottle is shaken to nucleate ice? Remember, the freezing takes little time, so the basic assumption is that the total thermal energy of the bottle remains unchanged, before and after freezing.  You should be able to get this answer accurate to 2 significant figures. So we can answer the question: did we drain all the water, or were we weighing both water and ice?? 

[Useful numbers for heat capacity, Latent heat and density: Cp water 4186 J/kgC, Cp ice 2097 J/kgC, Lh 333500 J/kg, density of water 1000, density of ice 920 kg/m3.]

2.    Questions on the Clausius-Clapeyron slope of the ice phase diagram

A Calculate the pressure melting point (the temperature at which the ice would melt) under the ice in central Greenland, assume the ice is 3000m thick?

B Assume the ice is at this calculated temperature, and that it has been for 1000s of years; is it melting due to the pressure?