As the saying goes, swallows fly low and it will rain. How do they perceive the weather?

Swallow flying low is considered as a sign of rain, and it is also a natural common sense to judge the weather conditions. How do they perceive the weather?

The value of biology in nature is that it is conducive to a relatively more balanced energy distribution in nature, and the energy transfer ability of biology is the basis of natural selection. In addition, the theory of energy flow evolution also believes that the evolution of organisms is the result of the contradiction between the demand of energy donors and energy receptors in the environment for energy transfer ability and whether the energy transfer ability of species can meet the needs of the environment. Swallows are summer birds, which are widely distributed in China. They fly from the south in spring and fly back to the south for the winter in autumn. Because of its large number, it likes to nest near people, so it is well known and loved by people. Whenever it rains, because the water vapor content in the air increases sharply, most insects can't stretch their bodies and fly freely because their wings are wet, so they can only crawl along the ground or fly close to the ground. Swallow-mediated energy flow can be expressed as "insects → swallows → oxygen". The energy of insects is higher than that of oxygen. According to the demand of energy distribution in nature, the energy in insects needs to be released, that is, insects and oxygen need an energy transfer ability to reduce the energy potential difference between them. Swallows can convert the energy in insects into heat energy that is relatively easy to transfer in nature, so they have the energy transfer ability needed by nature.

When it rains, there are relatively few insects in the sky. Therefore, insects and oxygen, two substances with poor energy potential, have low demand for energy transfer ability, that is, low demand for swallows. Swallows reduce the energy transmission ability of species by reducing the number, which shows that the number of swallows in the sky is relatively small. On the contrary, near the ground, there are relatively more insects, so the requirements for the energy transmission ability of swallows are higher. Swallows can enhance the energy transfer ability of species by increasing the population number to meet the needs of the environment, which shows that there are relatively many swallows near the ground.

Swallows fly low, which is essentially the result of the natural environment's choice of their energy transmission ability.