How did swallows, magpies and tadpoles become meteorologists?

Swallow Swallow flies low, indicating that it is going to rain.

Because the air humidity is high before it rains, the wings of insects are wet. Therefore, the flying ability of those insects as swallow food is greatly affected, and they can only fly near the ground. So swallows also lower their flying height and look for their own food-insects near the ground.

Little bees leave late and return early, which indicates that it will rain.

It turns out that the front and rear wings of bees are very thin and easy to fly. Bees are used to flying in sunny weather and high pressure. Before the rain, due to the increase of water content in the atmosphere, high humidity and low air pressure, bees are easy to get wet by tiny water droplets, gain weight, make their wings soft and heavy, slow down the frequency of flapping their wings, and have difficulty flying, so they have to stay in the hive.

The tortoise is sweating, and it will rain soon.

The reason is that the temperature on the turtle's back is slightly lower than the air temperature.

Before it rains, the air pressure is low, and the humidity in the air increases. When it is cold, the water vapor condenses on the turtle's back, just like sweating, which is essentially from the moisture in the air.