The ice cometh: A few facts and figures

To get to know the ice on your lake, it helps to know its physical properties. Here are a few worth noting.

•         Density: 0.916 grams per cubic centimeter at 32 degrees F. For comparison, the density of water is one gram per cubic centimeter.
•        Stiffness modulus: This is a measure of how stiff a material is. The stiffness modulus of ice is about 1.5 million pounds per square inch – or about three times as stiff as a hard plastic.
•         Heat of melting (or heat of fusion): 80 calories per gram. This is the amount of heat required to melt a gram of ice that starts at a temperature of 32 degrees F.
•         Heat capacity: This is the energy required to raise the temperature of a gram of ice one degree Celsius: 0.50 calories per gram. Interestingly, this is only half the heat capacity of liquid water.
•         Fracture toughness: This measures how easily a crack spread through a substance. Ice is about one-tenth as tough as glass in this respect.
•         Thermal conductivity: Ice conducts heat almost four times as well as water.
•         Refractive index: Light travels more slowly through a solid material than through air or a vacuum. The speed of light in ice is about 75 percent of its speed in a vacuum.