Similarly, even though the wind passes through and the temperature remains unchanged, why is it that the shade of a corrugated metal roof is hot while the shade of a tree is cool?

Radiant heat refers to electromagnetic waves such as far infrared rays. When you have a bonfire in a drum can, your body warms up even though the wind is blowing. In this way, radiant heat transfers from the higher temperature area (the drum can) to the lower temperature area (the human body) regardless of the air. Radiant heat = electromagnetic waves

The reason why a folded plate roof is hot and the shade of a tree is cool The shade is cool because the leaves are heated by the sun, and the moisture inside them evaporates as latent heat, taking away the heat from the leaves. This cooling effect on the underside of the leaves means that the shade does not emit radiant heat towards the human body, making it feel cool. *The leaves absorb the radiant heat from the human body. The temperature of a folded plate roof can reach 70°C to 80°C in summer. The skin temperature of the human body is about 32°C to 33°C, so the radiant heat from the folded plate roof is directed towards the human body. Thus, even in the same shade, the perceived temperature can vary greatly depending on the presence or absence of radiant heat.

Principle of Heat: Heat moves from high to low. The temperature measured by a thermometer (the air temperature) has a directional characteristic, with higher temperatures at the top and lower temperatures at the bottom. This is because warm air becomes lighter and rises. However, radiant heat, being electromagnetic waves, does not move in a fixed direction like air; it travels in all directions, 360 degrees. Following the principle of heat transfer, it moves from areas of high temperature to areas of low temperature, so the radiant heat from a standing seam roof that reaches over 70°C in summer radiates towards the cooler indoor environment.

Effect of Thermal Insulation Materials Thermal insulation materials are most effective in preventing "radiant heat," which is transmitted through infrared radiation, among the three types of heat. It is said that about 75% of summer heat is due to this radiant heat, so preventing radiant heat contributes to heat mitigation. Please watch the video that shows a thermal image of the temperature rise after a certain period of time, with insulation and thermal insulation materials placed at the same distance from an electric heater that generates "radiant heat." From this video, it is clear that thermal insulation materials are effective in efficiently blocking the "radiant heat" emitted by the electric heater. (Experiment video is posted above)