The principle of "good shade under the big tree"

We all know that the temperature under the tree is lower than the outside world. This is the old saying "having a good chance under the big tree" since ancient times. We can't help but wonder why this is the case. Let Xiaobian make science popular for everyone.

1, the principle of direct light. The light is blocked by the leaves and cannot directly reach the ground. People's skin cannot touch the sunlight and the human body does not feel the temperature of direct sunlight.

2, photosynthesis of plants. The leaves convert part of the solar energy into chemical energy that is stored in the plant. Therefore, under the big tree, it will absorb less solar energy than the bare ground and the temperature will be lower.

3, the water in the leaves for transpiration (ie, water evaporation), from the surrounding heat, will reduce the temperature under the tree.

4, the tree ground humidity. The ground temperature of the trees is lower than the temperature of the ground where the sun shines, and the humidity indicates that there is much moisture, so it is larger than the heat capacity of the generally dry ground, and the temperature takes a long time to rise.

5, fast air flow. Uneven heat under the big trees makes the air flow and accelerates the airflow under the big trees. The faster the air flows, the lower the temperature.