Fashion physics
- Hats and scarves can serve the same function. By reducing the amount of skin exposed to cold air, they help keep you warm. Mittens or gloves do this as well.
- Layering clothes allows you to adjust to changes in temperature between indoor and outdoor classes, as well as changes in the weather from a bright, sunny day to a dark, cold evening.
- Synthetic fabrics that block wind and water, like coats and snow pants are important for outer layers. The actual temperature may not seem too bad, but wind chill can drop the temperature anywhere from five to 30 degrees.
It takes more than putting on the season’s fashions to stay warm – you need to know how to wear them. Physics professor Pat Arnott, said the answer lies in layers.
He suggests starting with a thin layer, like long underwear, under your clothes. Then wear a thicker material, like jeans on bottom and a sweater or several long-sleeved T-shirts on top. Finish off with a thin jacket that will break the wind.
“A hood’s good because it doesn’t mess up hair as much as a knit cap,” Arnott said.
Adding gloves or a scarf helps cut down on cold too.
Arnott said layers work in four ways to keep you warm: minimizing exposed skin, trapping air between layers, combatting temperature changes and cutting down on the wind factor.
Minimize exposed skin
Any skin exposed to outside air temperatures will cool at a faster rate than covered skin. Arnott referred to this as thermo conductivity, which is the rate heat will transfer from high (or warm) temperatures to low. Covering up is an obvious one, but wearing gloves, hats or jackets with hoods will minimize exposed skin and thus minimize the amount of surface area that loses heat.
Arnott said longer hair and beards can help minimize exposed skin, too.
“Wait until summer to get that shaved,” he said. “Put on a moustache and beard. Put more material between the inner layer and the outside cold.”
Thicker fabrics will also slow the escape of heat more effectively than thin materials, he said.
Trap air between layers
Another thing to consider is how clothes are layered. The most effective thing to do is trap warm air between two layers of clothes. The layer of clothes against the skin is going to be close to skin temperature, whereas the outer layer is going to be the temperature of the outside air. If you trap air between the two, it will warm up and keep the heat from moving out.
“It’s giving a resistive layer against the heat or cold when it’s hot on one side, cold on the other,” Arnott said. “I want to wear something with an air barrier and no cold air coming in.”
Tucking jeans into boots or making sure coats are fitted at the wrists will create the seal to keep the colder air from coming in and keep the air already inside the layer warm.
Again, it’s important to consider fabrics when trapping air close to the body. Arnott used a knight’s metal suit of armor as a bad example. Although it would hold air inside, it would be a bad choice of garments.
“It’s large, cold and easily transfers all the heat,” he said. “Don’t wear a knight suit.”
Skin-tight clothes as the only layer, like tights, are also bad because they’re only a thin barrier that rapidly lets heat escape, he said.
Dealing with temperature changes
Layers serve another important function in climates like Reno, Arnott said. With temperature changes throughout the day, as well as moving from inside to outside, layers allow you to add on or take off clothes as needed.
Walking through cold weather demands warm clothes, but once in class, it’s important to be able to take off layers to prevent overheating and sweating, which can lead to dehydration. Being dehydrated will affect how your veins transfer heat and will make you feel colder, he said.
“Layers are useful if you get in a classroom that’s really hot,” Arnott said. “Take off, then put them back on to go to a colder outside.”
Layering is also important even if you’ll be outside the majority of the day because of the weather in Reno.
“That’s probably the biggest effect that we have here that’s out of the normal,” Arnott said. “It can be surprisingly warm, but as soon as the sun goes down, it gets cold.”
Don’t forget the wind factor
Wind can make temperatures feel colder than they are. Arnott said if the temperature is 15 degrees Fahrenheit and the wind is 20 miles per hour, the wind chill will make it feel like -2 degrees Fahrenheit.
“You have to pay attention to that,” he said. “Especially on windy days, minimize exposed skin.”
A good way to fool the wind chill is to make your outer layer a windproof jacket with a hood. Make sure your windproof jacket is made of a synthetic material that will resist the wind.
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