Layering - How Does It Work
Layering to keep warm in cold weather is really a matter of insulating your body so that you retain your body heat. Layering typically consists of two to four thermal layers depending on the temperatures you'll be exposed to. Each layer is designed to trap air. The more air that is trapped inside a material or fabric, the better it will insulate. The two most common layers are a base layer or thermal underwear layer and an outer layer. Then, depending on your level of comfort and how cold the temperature is, you can add middle layers for extra warmth.
The great thing about layering is that it allows you to adjust your comfort level as temperatures change or as your activity level increases or decreases. As you get hotter, you can remove a layer. As you get colder, you can add a layer. Once you understand how layering works, you can adjust your own layering system based on your own comfort requirements and the weather conditions you'll be experiencing.
Layering - Types of Material To Wear For Each Layer
Now that you have an idea of how layering works, let's go over the different types of layers that will insulate you most effectively. Your first layer is your base layer or long underwear layer. Depending on the temperatures you're expecting to face, this layer can either be a thin single layer garment, a midweight two layer garment or a heavyweight two layer garment. As mentioned earlier, as you come to understand how layering works, you will know what weight or thickness you will need as a next-to-skin base layer. The type of fabric you wear is important. You need a material that will wick sweat, retain heat, and dry quickly. Some examples of the most commonly used materials are merino wool, polyester , and polypropylene. Each of these fabrics retain heat even when wet. Cotton thermals do not. The only time you'd consider using cotton is if you were not going to be very active.
Now, let's skip to the outer layer. The outer layer's job is to block wind, snow, or rain from penetrating your inner layers and robbing you of heat needed to keep you warm. Your outer layer would be a coat, jacket, or parka that is waterproof, windproof, and breathable. Many coats will have built in insulation while jackets and parkas may just be a shell with the option to zip in an insulating liner.
The reason I skipped to the outer layeris because what you wear in between the base
layer and the outer layer all depends on your level of activity as well as how cold the temperature will be. A good base layer and outer layer is often sufficient for most winter weather conditions. During an average winter season, a good base layer and outer layer would be sufficient for skiing and snowboarding. However, if your combined base layer and outer layer are not warm enough, then you'll need to add an additional middle layer. This layer is typically a thicker layer of fleece. A merino wool, polyester or polypropylene fleece jacket and pants are recommended. A fourth layer is only needed in extreme cold weather conditions such as winter snow camping or summitting a high mountain peak. A fourth layer would be a heavyweight baselayer over a lightweight or medium weight base layer.
Layering - Thermal Base Layer Is Critical
Your next-to-skin thermal base layer is key to your comfort in cold weather. You want something warm, soft and dry against your skin. Not just any fabric can give you this. Cotton is still a very popular as a base layer because it is so soft. The problem with cotton is that if you begin to sweat, it absorbs all of that moisture holding it next to your skin. Cotton does not dry very quickly. When it gets wet, cotton loses it's ability to retain heat. This condition can lead to hypothermia if exposed long enough.
You need a performance fabric like merino wool, polyester, or polypropylene. Merino wool thermal underwear is super soft and 100% natural. It does a great job of managing moisture and keeping you dry. It also retains heat even when wet. It costs more than other thermals, but is well worth the price. Polyester and polypropylene are very similar. Both can be spun into a very fine thread making it extra soft and comfortable. Both of them are hydrophobic which means they repel water and dry quickly. Polypropylene retains more heat than any other fabric and it dries much quicker too. Polypropylene is probably the least expensive of these performance layering fabrics.
Layering - It's Never Too Cold With The Right Layers
Now that you know how to layer properly in cold weather, you can go out and enjoy the winter season. Don't be like so many others that sit inside depressed all winter long because they hate the cold. There is plenty of fun to be had throughout winter. All you need is the right layers!