Monday, October 27, 2014
TIP OF THE ICEBERG
Why does ice float? Ice floats in water because ice is less dense than water. The hydrogen bonds keep the molecules of ice farther apart than the molecules in liquid water. That makes the ice less dense than the liquid. Water is the only chemical we know of where the frozen state takes up more room than the liquid state. Anything else is the opposite.
The picture (left) came from a rig Manager for Global Marine Drilling in St. Johns, Newfoundland. These big ice bergs that calve off from glaciers often need to be towed or pushed away from drilling rigs. In this case the water was unusually calm and the sun was directly overhead so a diver got a nice clear picture of this estimated 300,000,000+ ton iceberg. As you can see 95% of the mass is below the water.
Sometimes as these icebergs flow south and melt they can completely roll over. Our ice on Georgian Bay doesn’t get thick enough to form real ice bergs. But the plates of ice flows do have more mass below the water than above. As the weather warms up the ice gets saturated with water and eventually begins to sink just below the surface until it melts away.