# Glossary | WeatherWear Weekly

Source: https://weatherwearweekly.com/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.

## Frequently asked questions

### Why does wind make 55 degrees feel colder?

Wind strips the warm air layer next to your body and replaces it with cold air constantly, so you lose heat far faster than on a calm day.

### What is the best outer layer for a windy fall day?

A fully closing, tightly woven jacket or coat with a collar. Wind resistance matters more than thickness for the outer piece.

### Are skirts practical on windy days?

Substantial midi skirts are. Light, full skirts lift and flap and will occupy one of your hands all day.