We usually take the little drops of water for granted, and rarely ever pause to ponder where they come from. Rain has its own story. A story of a long journey up and down the atmosphere, a cycle of transformation, of freezing cold, and liquifying heat. If we were to give a short answer, rain comes from the clouds floating high up in the sky. But is it really that simple?
In nature it rarely, if ever, is simple. In this article, we will provide you the whole grand process that leads to rain dropping from the clouds. We will speak of the water cycle, the formation of clouds and their floating around the sky as well as the the final step, the all too familiar falling of water drops: Rain itself. Finally, we will close the article by giving you a short explanation of the importance and necessity of rain.
The Cycle of Water
First, there is a fundamental truth in nature: Matter is neither created, nor destroyed. Thus, everything, rain, snow or hail is simply recycled water from some other source. This continuous recycling has no real starting point nor any foreseeable end. It is realized by a certain pattern, which follows these next, few steps:
- The sun heats water sources around the Earth – oceans, seas and rivers, for example.
- The heated water evaporates into the air as vapor.
- Rising air currents raise the vapor up and up into the atmosphere, until the cooler temperatures condense it.
- The condensed water vapor forms clouds.
- As clouds move around the skies, they collide, grow and start falling out of the sky as precipitation – in other words, rain, snow, hail or sleet.
- The falling water eventually gets back to the various water bodies around the Earth. And thus the cycle begins once more.
- The cycle repeats ad infinitum.
What is a cloud and why it floats?
Clouds, essentially, are a composition of water droplets or ice crystals that have settled on dust particles in the atmosphere. They are formed when the rising water vapors freeze, due to the much colder temperatures that exist up in the sky. The main reason they exist is due to how the sun heats the vast water bodies of the Earth, effectively converting them into vapor. There are, however, other ways a cloud can be formed. For example, in cases where different streams of air converge, they force each other to rise higher and higher. This usually creates cumulus clouds.
Why do clouds float? The short answer is that the tiny particles that compose them are so small that they are practically immune to the effects of gravity on them. An easy way to understand this is to regard a ray of sunlight going through your window. If you stare it, you will likely notice small, dust particles floating around in the air. These are so light that they are lifting by the air current, and gravity is unable to pull them down. Well, this is exactly what happens in the case of clouds.
What makes rain fall?
First of, it is important to realize that water is continually evaporating and condensing in the sky. In other words, parts of a given cloud are constantly disappearing, whereas new parts are constantly growing. If you are wondering why is it not raining constantly, if this process never stops, the answer is quite simple: Most of the water clouds does not fall as rain because its dropping speed is not nearly enough to overcome the updrafts that keep the clouds high.
For precipitation to take place and rain start falling, a water droplet needs to develop a fall speed which exceeds the cloud updraft. This is no easy task. To put it into perspective make note that for a single raindrop to form, millions of water droplets are required to collide.
Assuming enough droplets are gathered and they do end up becoming adequately heavy to start falling, again, there is no guarantee that they will fall down as rain. If the weather is very cold, they might freeze and turn to snow, sleet or hail.
Why Rain Is Important
Through the aforementioned process of precipitation, fresh water is created. This is due to how water leaves behind its salt whenever it gets evaporated. Many species, humans included, depend on the availability of fresh water in order to survive. Without rain, life forms depending on fresh water would have evolved differently – if they had evolved at all.
Moreover, rainwater is essential in the transportation of nutrients and minerals that flow from land to the sea. There is a great number of species living deep in the oceans that do in fact depend on these minerals. Without rain, all these species would have probably become extinct.
All in all, no matter how you see it, rain is an integral part of life in our world. Without rain, without the previously described never ending water cycle, the Earth would be a vastly different place than what we have come to know, survive and eventually thrive on.
By this point, you should have clearly understood where rain comes from. You have been armed by a basic yet solid understanding of the essential steps that form the continuous water cycle, and you have scratched the surface on why do clouds float and what exactly does make rain drop after all. Finally, we gave you a few reasons why rain is a vital process for sustaining life on Earth.
Hopefully, next time it starts raining and you start getting unwillingly wet you will pause. Instead of getting mad that you forgot your umbrella at home, you will think of this article you just read. Rain should be welcomed whenever it falls. It practically spreads life. We should try to enjoy it, whenever we can, or, in case that is impossible, we should at least try to not mind it too much.