What makes certain fabrics ‘breathable’?
Breathability is a measure of how easily water vapour can move through a fabric. We cool down by sweating, and breathable fabrics allow evaporated liquid to circulate and escape. Whether a fabric is breathable depends on the fibre and the weave. Natural fibres, like cotton and linen, draw liquid away from the skin, whereas synthetics, like polyester, tend to repel water. Open weaves with lots of holes allow air to circulate, while tight structures stop the air flow.
Weather data is recorded from around the world by automatic weather stations
Wool contains lots of trapped air, allowing water vapour to circulate