WINTER’S WAYS.

Waikato Independent, Volume XXII, Issue 2576, 25 July 1922, Page 7

WINTER’S WAYS.

It is colder in a thaw than in a hard frost ; do you know why ? The reason is that when frozen water is thawed ■it absorbs considerable heat from the air, thus reducing the temperature by many degrees. Salt flung on ice-covered pavements, etc., has the effect of turning the ice back into water. The reason is that ordinary water freezes at 32 degrees, but salt-aiul-water will not freeze till the air is four or five degrees colder. Hence the ice dissolves until the temperature sinks to the necessary point. Frost makes the earth crack because the water absorbed in the ground is frozen, expands, and forces the earth apart, ice requiring more room than water. A mixture of salt and snow is much colder than snow itself because the salt dissolves the snow crystals into a fluid, and whenever a solid is converted into a fluid heat is absorbed and the cold made more intense. If three pounds of snow be added to one pound of salt, the mixture will fall thirty-two degrees below freezing point !

Many of us welcome the coming of a frost because we are aware that it will he warmer—but do we know why ? The reason is that when water freezes it gives out its latent, or contained heat into the atmosphere, and at once raises the temperature. Certain lakes will not freeze, or freeze badly, because of their depth, and the fact that they are supplied by springs which bubble from the bottom, preventing the water of the lake from reaching freezing-point.