The rain is not dry enough.

The ancients said, "The water in the sky is the cleanest in the world." So is this really the case? Or is there another Gan Kun? We don't know. However, with the development of science and technology, this mystery may be solved. Ok, let's prove it with experiments!

Let's do an experiment. First, prepare a bottle, use this bottle to collect rainwater, seal it, and put it somewhere for 2 ~ 3 days. If there is no sediment in the bottle, it proves that what the ancients said is true. On the contrary, if there is sediment in the bottle, it means that the rain is not clean. And the experiment showed us a lot of precipitated substances. It turns out that the rain is not clean. You may ask, "Why is this?" As we know, rain is formed by condensation of water vapor in the sky. When the water vapor reaches the sky, it will be clean. Because the sky is full of a lot of dust and bacteria, when water vapor condenses into raindrops, some dust and bacteria attach to the raindrops, so the rain is unclean.

If you still don't believe it, do another experiment. First, find a transparent and sealed clean container, insert a hygrometer into the container to measure the humidity, and connect it with a kettle filled with water through a pipeline. Then, light the alcohol lamp under the kettle to make the water boil, and the water vapor will be injected into the clean container from the kettle through the pipe. In this way, the relative humidity of the clean container will continue to rise. When the hygrometer shows 65,438+000%, clean around the container.

What is the reason? Originally in a clean container, when the humidity reaches 300% ~ 400%, condensation will not occur. At this time, as long as water-absorbing particles are added, condensation will occur immediately. Because water vapor molecules are too small, the water droplets gathered only by water vapor molecules are also very small. The water vapor pressure in the actual atmosphere often can't make them form small water droplets, even if they do, they will evaporate quickly, but the water-absorbing particles are different. They are much larger than water vapor molecules and have great attraction to water vapor molecules, which is beneficial for water vapor molecules to gather on them and is not easy to evaporate quickly.

In the actual atmosphere, a large number of solid suspended particles, such as dust, smoke dust and volcanic ash, are floating. Most of these solid suspended particles come from aeolian dust, volcanic eruption and industrial emissions. When the water vapor in the atmosphere reaches a certain level, the water vapor molecules condense around the suspended particles to form small water droplets, and many small water droplets gather and merge into raindrops. When raindrops are big enough, the air can't hold them, so they fall to the ground in the form of raindrops, which is usually called rain. The particles deposited in the original rain bowl are dust, smoke and volcanic ash, which act as condensation nuclei.

It can be seen that the rain looks crystal clear, but it is not clean. There is still a lot of knowledge worth exploring in nature that needs to be discovered and studied.