Meteorologist Brent Watts
7:00 AM EST, January 23, 2013
As temperatures dip to the teens and single digits at night, ponds and other bodies get covered in a layer of ice. It's tempting to walk out on it, but don't.
Temperatures get cold enough to make the ice, but don't stay cold enough to keep it frozen solid.
Daytime temperature fluctuations can easily cause cracks in the ice, making it extremely dangerous to walk on. Even animals shouldn't be out on the ice.
The graphic above highlights the average thickness needed to safely walk on the ice.
You can't judge the strength of ice just by its appearance, age, thickness, temperature, or whether or not the ice is covered with snow. Strength is based on all these factors.
There is no such thing as 100% safe ice.
Here's some cold, hard facts about ice.
New ice is usually stronger than old ice. 2 to four inches of clear, new ice may support one person on foot, while a foot or more of old, partially¿thawed ice may not.
Ice seldom freezes uniformly. It may be a foot thick in one location and only an inch or two just a few feet away.
Ice formed over flowing water and currents is often dangerous. This is especially true near streams, bridges and culverts. Also, the ice on outside river bends is usually weaker due to the undermining effects of the faster current.
The insulating effect of snow slows down the freezing process. The extra weight also reduces how much weight the ice sheet can support. Also, ice near shore can be weaker than ice that is farther out.
Booming and cracking ice isn't necessarily dangerous. It only means that the ice is expanding and contracting as the temperature changes.
Schools of fish or flocks of waterfowl can also adversely affect the relative safety of ice. The movement of fish can bring warm water up from the bottom of the lake. In the past, this has opened holes in the ice causing snowmobiles and cars to break through.
A good rule of thumb is DON'T GO OUT ON THE ICE!
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