Black and white are not just for color, but for combining with matter. It depends on the size and material of the material. This should refer to the difference in heat absorption and heat dissipation of black and white materials under the same material. Under the same circumstances, the same substance, different colors, under the condition of heat radiation, there will be different conditions in temperature and heat release. The fundamental reason for the endothermic exotherm is that: After the substance absorbs heat, the molecules expand and the inter-molecular gaps open. When the substance stops absorbing heat, the molecular gap gradually recovers and the heat is released. The black substance has a strong ability to absorb heat radiation, and the temperature rises rapidly. The white matter has a weak absorption capacity for heat radiation and a slow temperature rise. The white matter absorbs less heat, and the intermolecular gap is small, and the amount of heat released is naturally small. Therefore, the general shade nets are all black. The subject is confused that the heat absorption will cause the heat to accumulate under the net. In fact, the black matter absorbs heat only because its temperature rises. Just like you put a parasol with vinyl in the summer to go out, it is obvious that you are walking under the umbrella. The temperature is a little lower than walking directly on the road, but the umbrella cloth is particularly hot, but this does not hinder the person holding the umbrella. But if you wear a black shirt and go out for a turn, it won't work. The distance is short and the heat is passed directly. As the Taoist friends said before, the greenhouse has a certain height, and the flowers and trees are not directly in contact with the shade net, so it is cool.