Rain can be a marvelous thing, and it can also be a disastrous problem. We get too little rain and we will wind up being in a drought, with little to no water available for the crops, plants and trees as well as humans and animals. On the other hand, we can get too much rain, which will equate to flooding, and can also wreak havoc on crops, other plant life and trees. It can also be a big problem for local populations, ruining homes and businesses, and disrupting local economies, and displacing people as well as local wildlife populations.
Why Does it Rain?
In the simplest explanation we give for why does it rain, we will break it down into four basic steps. First of all, the air heated from the sun, or warm air turns the water from our lakes, rivers, streams, and oceans into water vapor, which is the gaseous form of water. That water vapor is lighter than water in its liquid form and rises into the air.
The water vapor that has risen from the evaporation process turns into clouds as it rises higher into the atmosphere. The clouds contain small droplets of water or ice crystals, all dependent on the height of the clouds and the air temperature in the cloud.
As we go higher and higher as clouds do, the air also gets increasingly colder and colder.
When the clouds amass too much water vapor and it becomes too heavy, that is when it returns to the ground in the form of rain, sleet, freezing rain, or snow to complete the cycle.
For a more in depth look at the water cycle to understand why does it rain, one has to look at the movement of water itself. The actual path that any water molecule follows in a complete cycle can vary and complex and doesn’t mean that it will exactly follow the path shown in even the most complex water cycle diagrams.
Another point of interest is that the diagrams omit the actual amount of time which molecules of water take as they travel through the complete cycle. For an example of how complex this can be, a water molecule starting off in Antarctica may actually take over 250 years to travel along the bottom of the Pacific Ocean before it resurfaces near Alaska. We also know that water can be frozen as a solid in a glacier or ice sheet for many thousands of years before it melts and returns to liquid form again.
Another important point to consider is that water molecules may change states, going from liquid to gas to solid as it travels through the cycle. It even travels underground where it can seep through grains of dirt, sometimes returning to the surface through artesian springs.
Water vapor, or the gaseous form of water is not visible to the naked eye, but we can see it in the form of fog and clouds in the atmosphere.
Living organisms can also move water around as it is consumed as a liquid or extracted from food and carried within the organisms body. It then leaves the body as a gas during exhalation, is excreted, or may even evaporate from the skin in the form of perspiration. Plants are known to be effective movers of water. The roots gather water and distribute it throughout the plant. While some of it is used in the process of photosynthesis, most of it will travel to the leaves and will evaporate easily.
Resources: NOAA Education Resources: Water Cycle
So understanding the water cycle is important in understanding why does it rain. It can make significant impacts on our daily lives, and either positively or negatively effect both local and global ecosystems, and even in some instances economic systems.