A garment’s wind resistance is a function of its composition fabric and design features rather than a function of the fiber composing the fabric.
Garments with the greatest wind resistance will be made from low-porosity fabrics that provide a physical barrier to the wind. Yarn gauge and tension, weave or knit architecture, and tightness/weight determine a fabric’s level of wind resistance. The garment design will include features that prevent air movement into or out of the garment interior. Storm collars or hoods, positive closure cuffs, bottom hem drawstrings, and plackets covering zipper closures are some basic design features.
Most wind proof or resistant garments are very effective at stopping air movement. However, they also prevent moisture movement and when wind subsides, over-heating and perspiration results. Though Altiplano garments are not focused on wind resistance, many clients prefer them for windy conditions. Because they manage moisture levels so well and maintain a comfortable temperature, they find wearing a tighter weave outer or inner layer (such as a cotton twill) with their llama fiber garment will give a very nice balance of wind protection and temperature regulation.
Outdoorsmen such as Brandon (video) will cite wind resistance as a property of our clothing and everyone wearing the Vaquero jacket will note its double layer construction as windproof when worn in subzero wind chills. When high wind conditions are encountered, there is often associated moisture. The llama garments are ideal to wear under shells that are both water and windproof. Typically a light llama fiber mid layer such as the half zip will maintain comfortable temps under A shell when worn in wind chills in the 10-20 degree F. range.