WeatherWear Weekly glossary
Base layer
The thin next-to-skin layer (merino or technical fabric) that manages moisture and provides bulk-free warmth.
Mid layer
The insulating layer between base and shell - knit, fleece, or light down - whose job is trapping air.
Shell
The outer layer that blocks wind and water; contributes almost no warmth itself but multiplies the layers beneath.
Fill power
Down's loft rating; 600+ fills city-winter duty, 800+ is expedition grade. Higher means warmer per ounce.
Storm placket
The fabric flap covering a coat's zipper or buttons that stops wind and rain entering through the closure.
Thermal regulation
A fabric's ability to keep you warm in cold and comfortable in mild conditions; merino wool's signature property.