What does convection do to a woolly jumper?

Convection causes warm air to rise and cooler air to sink, creating a circulation pattern that can affect a woolly jumper. When a woolly jumper is worn, it traps warm air close to the body, which helps retain heat. However, if the jumper is exposed to a cooler environment, convection can draw heat away from the body, making the jumper feel colder. In essence, convection influences the thermal insulation properties of the woolly jumper by regulating the air temperature around it.