What is the layering system?
A “layering system” is a way of dressing for cold weather that effectively balances the competing needs of insulation, mobility and breathability. This typically consists of three layers, a base layer, mid layer and outer layer, consisting of a “shell” or insulated jacket — although this will depend on the environment, conditions and activity you’re getting involved in.
Get it right and the optimum layering system will keep you warm, dry and comfortable in adverse conditions, allowing you to complete the task at hand. Get it wrong, and you will either freeze or overheat, and excessive sweating will cause your body temperature to plummet dramatically in cold climates.