In general, three layers are advised, depending on the work to be done and the outside temperature. If few items are carried, the body cools immediately. If too many garments are worn, you sweat so much that your clothes get wet and you even catch a cold.
It is advisable to distribute the layers of clothing in the following order:
First layer: it is tight to the body, imitating a second skin, and is composed of long-sleeved T-shirt and long pants. Its function, absorb moisture and keep the skin dry and warm. The natural fibers (wool and merino) are ideal. Also synthetic ones, like the polyester or certain type of plastic membranes of high technology. Cotton is discouraged, as it moistens and cools the skin. You should also wear extreme cold weather socks.
Second layer: it conserves the corporal heat, isolating the humidity that absorbs of the first one and sending it towards the outer layer. The garments are slightly looser than those of the first layer, they must have a wind-breaker and, in their preparation, synthetic fibers are strongly recommended.
Third layer: the outermost, which covers, protects and serves as a barrier against wind, rain and snow. It needs to be waterproof. The dresses have to be loose so that they do not press the two inner layers. Therefore, a larger size than usual is recommended. Winter coats for this level are usually made with a mixture of synthetic and natural materials. For example, synthetic fur jackets with feather fillings. In fact, the one made with synthetic fibers is lighter. To this it is added that, for ecological reasons, many discard the use of animal skin, although there are some that prefer this material.