Why is merino wool so warm?

Merino wool has excellent insulating properties. The fine and strongly curled fibers lie very loosely on top of each other, so that air chambers form between them. As a result, there are fewer points of contact between the material and our skin, which means less heat is dissipated. Air is a poor conductor of heat and reduces heat exchange with the material. You can compare this effect with a double pane in the window. The two panes, with the enclosed air in the middle, keep the heat in the building during the cold season and the heat outside in the summer for a comfortable room temperature.  The merino wool does not warm up by itself, but prevents the heat from escaping thanks to its air pockets such as the double pane of glass. In cold temperatures, it keeps the heat on the body and thus protects us from the winter cold.