The temperature is 40 degrees, higher in the sun and on the ground, higher than the normal body temperature. At this time, the cotton-padded jacket has played a role in heat insulation, isolating the external heat from the human body and playing a certain protective role. The cotton-padded jacket has poor thermal conductivity and strong thermal insulation, which is also the reason why the popsicle is tightly wrapped in the cotton-padded jacket and will not melt. It is warm to wear a cotton-padded jacket in winter. There is another reason, which is to prevent the human body from dissipating heat, increase perspiration, and also take away the heat of the human body. So it's hot to wear short sleeves, and it's cool to wear cotton-padded jacket. When the outside temperature is lower than the human body temperature, the clothes keep warm, and when the outside temperature is higher than the human body temperature, the clothes keep warm.