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How to Keep Warm During Winter

Working outside during the winter months can be hard going when it's freezing cold outside and you can't feel your fingers and toes. But... it doesn't have to be this way. With a bit of knowledge and the right choice of clothing you can keep warm and comfortable, even in the harshest of conditions. Here is a guide to being cold and how to avoid it (with help from our friends at Woolpower, a Swedish based manufacturer of the world's finest merino wool base layers).

What makes us cold?

A major contributing factor to feeling cold is wind chill. Wind increases the chilling effect of cold temperatures by literally blowing away the layer of warm air that's close to the body. The body then reacts by reheating the now-cold air closest to it, before it too is blown away and so on. As this process is repeated more and more, the body can become dangerously chilled.

Some facts about wind chill

At a temperature of -10c (14f) with winds of 18mph (8 m/s), the wind chill on bare skin equals a temperature of -27c (-17f) with no wind. See the table below for the effect of the wind chill effect at different wind speeds and temperatures.

Wind Speed (m/s)Air Temperature (c)
00-5-10-15-20-25-30-35-40
2-1-6-11-16-25-27-32-37-42
5-9-15-21-28-34-40-47-53-59
8-13-20-27-34-41-48-55-62-69
16-18-26-34-42-49-57-65-73-80
25-20-28-36-44-52-60-69-77-85

 

The body in cold weather

The ideal temperature that we as humans have adaped to, over the course of thousands of years, to be comfortable with (without clothing) is 27c (80f). At this temperature our bodies work at their optimum, and maintain a steady internal temperature of 37c (98.6f).

In order for our bodies to work properly, we need to provide energy in the form of food and water. This enables our hearts to pump, our muscles to work and our braind to function. Approximately 70% of that energy is needed to maintain a constant core temperature.

Body heat is created by burning food, such as fat, carbohydrates and protein. Heat is products mainly in the muscles, and increases the more work the muscles do. In a cold environment the body needs external help to maintain it's temperature, we have to add extra energy by eating and drinking more, we need to keep active and we need to dress correctly to avoid getting cold.

When the body gets cold, it tries to create heat by shivering. The body can increase it's own heat production 4-5 times by shiver. The body also decreases blood flow to our hands and feet in order to proritise heat to the body's core, i.e. the heart, brain and other vital organs. This is why we first feel the cold in our hands and feet, even though the rest of our body feels warm.

Sweating, or perspiring, is a normal reaction when the body is too hot and needs to cool down the skin. The skin cools because then moisture (sweat) evaporates, and this function works very well in a hot climate. In cold weather however, when we are wearing lots of clothes, heavy sweating can be disasrous as the moisture will make us colder.

We lose between 0.5 to 1 litre of fluid from the skin per day due to normal evaporation (sweating), however during hard work this can reach several litres per hour.

Further reading - Dressing in Layers | Merino Wool - nature's own technical material

View Merino wool thermal base layers | View waterproof trousers

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