HOW COLD DOES IT HAVE TO BE TO GO ICE SKATING?
Everyone knows that ice forms from liquid water when it reaches 32°F (0°C), but just because frost has appeared overnight does not mean it is time to get your skates on.
That's because this temperature is only cold enough for a thin layer of ice over the top of ponds and lakes, which is fragile and could easily melt away.
Water freezes from the top down because, after it gets below 39°F (4°C), it gets less dense as it gets colder.
This cold water rises to the top, eventually forming ice.
The air temperature needs to remain below freezing for a long period of time to allow for thicker ice to build up below the top layer.
According to the Canadian Red Cross, ice must be about six inches (15 cm) thick for it to be skated upon safely.
The reason ice feels slippery is because when solid surfaces, like skating blades, move over it, the friction cause a very thin layer to melt.
The water reduces the friction between the object and the solid ice, making it more slick.
The amount of time it takes for a layer thick enough for ice skating depends on the water itself.
Currents and ripples, which could be caused by fish, mean that denser warmer water is mixed with the colder water at the top, keeping it warmer.
Friction between the moving water and the surrounding air or surfaces also contributes to its warming.
Any impurities dissolved in the body of water can work to lower its freezing point. The salt in sea water means it freezes at about 28°F (-2°C).
The middle of a body of water also takes longer to freeze than the edges, as the surrounding land helps absorb heat from water its in contact with and cool it quicker.
According to The Washington Post, experts say that it takes about two weeks of temperatures of near 0°F (-18°C) for lake or pond ice to freeze to a safe thickness.
The Rideau Canal Skateway has still not been opened this year as Ottawa is in its third warmest winter ever recorded, with temperatures hovering just below freezing so far this year.
Canada’s environment minister, Steven Guilbeault, said on Tuesday that this is an example of climate change in the country.
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