Water is the most abundant liquid on Planet Earth. It occurs in all three forms of Vapour, Water, and Ice. The oceans cover 71% of the Earth’s surface and contain 328 million cubic miles of water. In addition there are 120,000 cubic miles of fresh water, and 5.5 million cubic miles of ice, which if all should melt would raise the sea level by about 150 feet. There is also a lot of water in the atmosphere, and if all were deposited on the earth, it would be equivalent to a global layer of one inch depth , in other words the equivalent of 3,000 cubic miles of water.
Water is absolutely essential to life. 78% of our human bodies is water. Without any water, our planet would be dead. Nothing could live. Therefore an examination of the properties of water would be very instructive. In particular we shall look at the way in which water freezes.
If you were to melt some lead and pour it into a container, you would find that it solidifies from the bottom upwards. But doing the same with water, you find the ice forming on the top first. In fact, apart from ammonia, there is no other substance known to man which behaves in this way. Why does this happen?
The density of water increases as the temperature falls, but only until it reaches 4 degrees Celsius. Below that temperature water shows a slight decrease in density, meaning that as the temperature goes down, this colder water begins to rise to the surface and finally freezes, forming a layer of ice on top of the water.
This is an amazing fact of nature, one which sets it apart from all but one other substance. Imagine what would happen during a freezing winter if water behaved like lead. Ice would form on the bottom of ponds and lakes, and gradually build up towards the surface, depositing all the fish on the top of the ice, there to die. But because ice forms on the surface, it forms an insulating layer against the coldness of the air, and prevents the ice thickening too much. All living things in the water are therefore preserved during the freeze as they live in water at 4 degrees C beneath the ice.
The important point is that God has so ordered the structure of water that it freezes in the manner described. Our planet has been designed to preserve and foster life in all its forms. It is not a coincidence. It has happened this way by virtue of God’s handiwork at the atomic and molecular levels, and we are all able to benefit from it.
Having described this strange property of water in simple language, our next PT will be for those who would like to know more about the water molecule, and why it acts as it does. Surface freezing is just one of several peculiarities in the behaviour of water.