What is rain ?
Rain is a natural phenomenon, it appears in the form of drops of water coming from the clouds and falling towards the ground. It is one of the most common forms of precipitation on Earth.
There are two types of precipitation:
- Stratiform precipitation : it covers a large area, lasts a long time but is of low intensity. They occur in low pressure areas and troughs and are associated with stratus clouds.
Examples: drizzle, light rain…
- Convective precipitation : it covers small areas, does not last long but is intense. They are very localized and produced by the convective instability of the air. This precipitation is associated with “cumulus” clouds.
Examples: thunderstorms, showers, cyclones…
Precipitation can take a liquid form (rain, drizzle, freezing rain, freezing drizzle) or solid (snow, snow in grains, rolled snow, sleet, hail, ice granules, ice crystals).
Reasons why rain is important
1. Rain recharges groundwater
Let’s take stock of these natural water reservoirs and their role in the water cycle.Groundwater comes from rain and other forms of precipitation that falls in the watershed drained by a stream and its tributaries. Some of this rainwater seeps into the soil through the pores and cracks in the rocks. This infiltration phenomenon takes place in the unsaturated zone of the aquifer, called the vadose zone.Then by gravity effect, the water flows deeper into the empty spaces of the aquifer to form a sheet, that is to say an area saturated with water.Studies have shown that there is a relationship between groundwater recharge and rainfall in the tropics . Depending on the geological conditions the annual recharge of to shallow aquifers can range from 2% to 40% . Source
2. Rain is important for agriculture
Agriculture and rain are closely linked, since crops depend directly rainfall …
The rain is always welcome and good, except when the crop is wet or when the hay has already been cut and is waiting to be stacked or packed. Few farmers will complain about an excess of rain , since it might stop raining for months and suffer years of drought .
Even in areas where irrigation is available, rain is the preferred method of moisture for the crop, since it falls uniformly and is more beneficial to the soil than an equivalent amount of irrigation water. In that sense, irrigation systems using central Pivot apply water in the most similar way to rain.
Science has tried to cope with the shortage of rain by creating it artificially. At some point and when conditions have been considered adequate, silver iodide has even been scattered in the air to try to induce rain. Apart from not being beneficial for the environment, the effectiveness of this technique is not very clear, since hailstorms were produced shortly after applying the silver iodide and it is not known if this caused the hail or if it helped divide the hail in smaller particles.
3 . Rain is the best solution for forest fires
On the other hand, rain is also a huge palliative for tragic situations such as forest fires in which the presence and human action is very limited. When we talk about large fires (whether intentional or accidental) in natural areas, we cannot expect a solution other than rain since in this case there will also be very little the power of change of the human being with respect to that risk situation. Fires, in addition to damaging immense natural areas, can also become dangerous to nearby towns and settlements.
4. Rain is an important part of the water cycle
It is important to keep in mind that rain is a natural phenomenon that is part of the water cycle and therefore its presence is vital for life of any kind. Without the rain or precipitation the water cycle would be interrupted and the existence would not be the same since the soils would not be watered, the vegetation would not grow and the food chain could not begin.
5. Rain plays a role in cleaning the air of pollution
Rain is like a washing machine, if it is true that it cleans clothes, in this case, the sky, but it also has a centrifugal effect, that is, it pushes all the contaminating particles towards the ground. It is necessary to understand that the rain disperses the contamination , that is, every time it rains, the water drags the suspended particles to the ground it also come with wind which helps to move particles .
It depends on several factors that the rain helps reduce air pollution. The main factor is the size of the contaminating particles. For the very small ones (smaller than PM2.5, particulate matter or something like 0.0025mm particulate material) the rain does practically nothing. With a moderate rain, only 1.45% of these particles are removed from the air, and with a tormenton, only 8.7%.
For larger particles, PM10, the effect is greater. With moderate rains 10% of these pollutants are cleaned, and with thunderstorms 30%. Even so, they are not very high numbers to trust Tlaloc as a savior of air quality. The reason that the rain has more effect on larger particles is that it does not actually “wash” the air, but that it moistens the ground and other surfaces, trapping there the particles that would otherwise be floating ; It is something similar to when you want to sweep a dusty floor and to make it easier we wet the floor.
For countries such as India , China and South Korea pollution is really bad causing a number of respiratory illnesses among other citizens. These governments are developing plan to use artificial rain to reduce pollution. Source Source
6. Rain reduces the heat in our environment
Rain falls from a higher and colder altitude as it falls it absorbs the heat of the hot atmosphere make our surroundings cool. As the rain absorbs the heat it starts to evaporate, increasing the airs humidity. The air is now cool because of the humidity.
7. It helps to regulate the room temperature
Although it seems to us that the days of storm are gray and cold, the water helps to regulate and stabilize the temperature, during the cold seasons, the rainy days, it usually increases the ambient temperature and is somewhat softer than on clear days with low temperatures zero. As during summer, storms that occur with great force, always help reduce or lower that typical hot weather and cool the ground and with it the ambient temperature.