Temperature at the poles

Berkeley CA

Description

The air temperature at the poles can be quite high without ice starting to melt. This is because of the factor known as latent heat of fusion. The way this works is that heat from the air is gradually transferred to the ice until enough heat is absorbed to trigger melting, while all this time the temperature of the ice remains at 32 degrees Fahrenheit. Once the ice is melted, it exists in the liquid water state, whereupon its temperature can increase from that point on. The explanation for this situation is that the water molecules in ice are tightly bound to each other, requiring heat energy to loosen them enough to change solid ice to liquid water. Since water molecules are freer, it is easier to raise the temperature of H2O while it's in this state. Consequently, the water surrounding sea ice, for instance in the Arctic, can cause further ice melting. Additionally, the darker water absorbs heat from the sun more readily than does the ice. Thus a positive feedback is activated resulting in further melting. The role played by carbon dioxide is to trap heat (originating from the sun) in the atmosphere, making the air warmer than it would be otherwise.