(Host) A winter cold snap can mean different things depending on who – or what – you are. For the power companies, it’s a time of worry about overloaded grids. For plumbers it means working overtime on people’s frozen pipe. At the Montshire Science Museum in Norwich, it’s an occasion for curiosity.
VPR’s Susan Keese reports.
(Keese) It’s that time again. The squeak of subzero snow underfoot. Birds at the feeder with their feathers puffed out against the cold. These are the days when everyone could use an extra layer of insulation.
At the Montshire Museum in Norwich science educator Rachel Van Houton is demonstrating the insulating qualities of fat. Her audience is a group of toddlers and moms.
(Van Houton) “Okay, what I’m making here is just some ice water. Cold, huh?”
(Keese) Her tools are a tub of water, some ice and a double plastic bag, slathered on the inside with Crisco. She calls it a blubber glove.
(Van Houton) “And what you’re going to do is put one hand inside the blubber glove, and then one hand has no glove. And what you’re going to do is put both hands in the ice water. Which hand is warmer?”
(Keese) Van Houton says you could make a whole suit out of Crisco and really stay warm. That’s kind of what bears do when they eat and eat before it’s time to hibernate. Then they spend the winter living off energy stored as fat, and using the fat as insulation.
Van Houton says even humans would do well to add a couple pounds to help them stay warm at times like these. One of the moms asks how the birds keep warm.
(Van Houton) “Some birds will roost together. Some birds, like ruffed grouse, will actually just dive into a snow bank and the snow will insulate them.”
(Keese) Van Houton says many birds fluff their feathers. It’s like putting on a down coat.
(Van Houton) “Actually down is the layer under the feathers that you see. It’s made up of all these little fibers that trap air and the air gets warmed up by their bodies. And once the air gets warm, then it keeps them warm.”
(Keese) Mammals like fishers and foxes have similar fluffy layers of fur underneath their outer coats.
(Van Houton) “The ones close to the skin are really soft, and those are really fine and there’s lots of them and they trap the air. And then the outer fibers will protect them from the weather.”
(Keese) Humans have to buy their coats. But they have other advantages. Like heated homes and snowblowers and chemicals that melt the ice.
Van Houton uses a simple demonstration to show one of the most common ice-melting agents at work. She places an ice cube in a cup of water. She hands toddlers Casey Nichols and Max Pfeiffer a looped piece of kite string. She asks if they can use it to lift the ice.
(Van Houton) “Hmmm, that doesn’t seem to work, does it? We’re going to try something…”
(Keese) Van Houton lays the string on the ice cube and sprinkles it with salt.
(Van Houton) “You want to put the salt on?”
(Boy) “Yup, I do.”
(Van Houton) “Now sprinkle it right on the ice.”
(Keese) She asks them to wait a few seconds before they try to lift the ice cube with the string.
(Van Houton) “You want to try it? Oh, yay! Good job!”
(Keese) In the string demonstration, the salt melts the ice around the string but not the ice directly underneath it. When water from the melted ice hits the unsalted area beneath the string, it refreezes, bonding the string to the ice cube’s surface.
Van Houton explains, mostly to the parents, that salt lowers the freezing temperature of water. That’s why road crews use it:
(Van Houton) “So when you put it on the roads it means it has to be a lot colder before it turns to ice. So at 32 degrees the roads are going to be wet instead of ice.”
(Keese) When temperatures fall well below zero the way they have recently, Van Houton says, there’s not much salt can do. There’s not much anyone can do about it but dress warm – stay insulated, that is. And keep an eye out for nature’s little tricks, which can keep even the coldest days interesting.
For Vermont Public Radio, I’m Susan Keese in Norwich.
(Host) The Montshire Museum will host a special cold weather science event for children ages six to 10 on Martin Luther King Day, January 19th.