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How do you know when the ice is safe to go out on?

December 20, 2018
Windham

Well, we did have some cold weather recently, and some ice did form on some area waters. That was then, this is now! The short version is…I would not trust any ice on any body of water in southeast Nebraska right now.

The formation of ice is a science in itself. From the perspective of someone interested in the physical sciences, water is one of the strangest substances on earth. Most things get more dense and heavier as they get cold.

If water got denser and heavier when it froze, it would sink. Ice would either fall to the bottom of lakes and rivers or form there. Imagine the flooding we would see every winter as ice formed on river and stream beds and caused the water above it to be forced out of its banks and into surrounding areas.

One of the special qualities of water is that it actually becomes lighter below 39 degrees. This makes ice lighter and less dense than the water below it. This is why ice forms and floats on top of the water, rather than sink to the bottom.

For water to freeze and change into ice, it must be cooled to its freezing point. It loses heat to the atmosphere. Have you ever noticed the “fog” on the surface of open water when the temperatures are cold? That is the heat of the water going into the atmosphere. That heat loss occurs because the temperature of the air is lower than the temperature of the water.

For ice to get thick enough and strong enough to be safe to walk on, we need steady, below freezing temperatures. The colder it is for a longer period of time, the thicker and stronger the ice becomes.

There are a number of things that affect ice formation. Moving water under the ice will generally make the surface ice thinner than other areas on the same body of water. Springs can make localized thin spots (remember – heat rises so warmer water rises and thins the ice from underneath).

Vegetation along shorelines or in shallow areas can cause localized thin ice. Underwater vegetation will absorb heat as a part of their natural growing cycle. The vegetation can transfer some of that absorbed heat back to the water and create thinner ice above the plants. Have you ever seen a big stick or limb protruding from the ice, and noticed that there was a little bit of open water right around the spot where the stick came through the ice? This is why.

When you do decide to go out on the ice, go slowly. I like to test the thickness of the ice every few feet until I get comfortable that there is sufficient ice to support me. I never icefish alone and I always wear a lifejacket until I “know” the ice will hold me.

A lifejacket may not prevent me from breaking through the ice, but it will help keep me at the surface. Even if hypothermia sets in and I lose consciousness, my head is still above the ice and I can continue breathing. This fact alone makes a successful rescue more likely.

Any time I’m icefishing I have my designated sled with me. In addition to my icefishing gear, I have some other safety and rescue gear on the sled. For example, I carry 50-feet of rope attached to a Class IV flotation device. This is the flotation device that looks like a set cushion and is required to be in all boats. It is required so that you have something to throw to a drowning person. I carry one in my icefishing sled for the same reason.

I can easily toss this rig to someone who falls through the ice and stay back on more solid ice to pull them out. The weight of the Class IV allows you to throw more accurately and it pulls your life line out with it! This kind of flotation device can literally be a life saver for the person in the water.

I also wear a pair of icepicks around my neck. If I do fall through the ice, these spikes can help me get a “grip” on the surface of the ice and pull myself out. They say water on ice is the slipperiest thing in the world! Why?

In May of this year, a scientific paper was published in the Journal of Chemical Physics describing the properties and surface of ice. Researchers had found that it was not the liquid water on the surface of the ice that made it so slick; it was what they termed “loose water molecules”. The researchers made the analogy of it being like a dance floor covered with marbles or ball bearings. Slipping across the surface of the ice is simply “rolling” on these molecular marbles.

Ice normally has a very structured pattern of crystals is which each water molecule in the crystal matrix is attached to three other molecules. However, molecules on the surface of the ice can only be attached to two other molecules. The result is a very weak bond with surface molecules. These surface molecules shift and tumble when a tractive force is applied to them. To state it very simply, the surface of the ice can move under your feet. Score another one for science!

And…Merry Christmas!

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