James Miller

Weather for the Week of 2/9…Slippery Roads

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phase change diagram


There is not a lot of exciting weather this week.  We will get a little snow toward the end of the week.  The highs will get into the 20s, but the lows will be in the single digits, or below zero.  Wind chills will get below zero too.

The story is actually the roads.  Everyone knows they’ve been slippery and nasty.  Not just Manchester roads; M52, I94, and M50 have stayed slippery in spots for weeks.  So what gives?

It’s the cold, not the snow.  When temperatures get bitterly cold and stay that way, a few different things happen:

1) The pavement gets and stays cold.  When you talk about snow and ice on roads, the temperature of the road is just as important as the temperature of the air or wind.  Cold pavement actually causes the ice to bond to it and makes it harder to remove with a shovel or plow.

2) Road salt stops working.  At temperatures below 15F salt won’t melt the ice.  Road salt (chemically identical to table salt) lowers the freezing point of the ice, but it can only lower it so far (see above.)  If it gets any colder than that, nothing happens.  It just sits there and the ice stays like it is.

So, not much new snow, and school probably will not be canceled.  But roads will stay slippery.  Use caution.

For those who want a little more reading about road salt, and I know you’re out there, try this interesting piece from the Canadian Department of Environment.



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