The science of dressing warm
Posted 2nd February 2016
Your mum probably told you to wrap up warm or you’d catch your death. Or maybe you’re a staunch believer that a good hat is all you need.
But behind these beliefs is the science. We take a look at how your body works and the best ways to stay warm…
When to wrap up
Should you only wear your jacket outside to ‘feel the benefit’?
This is actually a bit of a tricky one as your body heats in two different ways – your core temperature and your skin temperature.
By keeping your jacket on inside, you heat up both your core and skin. Your body’s sensors will acclimatise to being warmer. So when you go outside, the quick drop in temperature will hit the sensors in your skin and it will feel colder as your body is used to being warm.
Over the long term, though, having a higher core temperature brought about by wrapping up warm indoors will slow the eventual cooling of your body’s core. Overall, it’s better to keep your coat on indoors and the initial shock should be tolerated in time.
On your head
Do you really lose 80% of your heat from your head?
While keeping your head and ears warm feels good, the idea that you lose the majority of your body heat from your head is simply not true.
The idea was apparently started in the army and through pseudo-scientists who argued that the high levels of blood vessels on the scalp lead to heat leaking out.
In fact, you lose as much heat from your head as most other parts of the body. Heat loss comes from exposed skin and the head represents just 10% of your body’s skin. The reason a hat is used and helps you feel warm is that usually, your head is the only part of your body that is exposed to the wind chill. But having a hat on or not shouldn’t affect your core temperature.
Hands and toes
Why is it important to keep your toes warm?
Ever wondered why the palms of your hands and soles of your feet don’t have hair on them. One of the reasons is that your extremities are used to help regulate your body heat.
When your core is nice and warm, it sends blood to your hands and feet to help regulate the temperature. Without gloves or thick socks, you could lose a lot of this heat. When your core gets cold, it stops sending blood to the extremities, keeping it in the centre to power your vital organs.
This means that gloves and socks stop being as useful, as the cooling comes from within. At this point, the best way to keep your feet and hands warm is often to heat up your core through either physical activity or increasing insulation.
Love the layers
Are more layers better than thicker ones?
As you’ll have noticed from the above, core temperature plays a big part in staying warm. And one of the best ways to keep it hot is to layer up.
The idea behind layers is that they create what is called ’dead air space’. This trapped air is heated by your body, acting as a blanket to keep you warm. As the air cools down, the heat is lost to the outside world, but is quickly heated again from the body as the air pockets are relatively small.
You might think getting fabrics that don’t allow air to escape is best for layers but it’s actually the opposite. Sealed fabrics also trap water vapour from your body. This cools down over time but cannot escape meaning you’ll have cold water on your skin.
You want breathable fabrics so water vapour can escape. Fabrics like wool wick this water away from your body first, so the cool effect of evaporation is limited and the air behind it can heat up to replace any lost warmth. Also, breathable fabrics allow the warm air to circulate around your body.