Hello great steemians, how are we doing today? And I hope our week is going on fine as well.
Today, I will be talking to us about artificial rainfall generation. I remember when I first heard about this topic, I taught it was a joke because to me I only believed it was only the African traditional rainmakers that can do that with their magical spells and the likes. Don’t ask me how they do it because I don’t know how they do it, lol. On the other hand, I never knew there is even a scientific approach to this topic. After making some research about the topic I got to know a lot more about it.
Image credit Pixabay. CC0 public domain license. Image by CrimeScene
Can rainfall be generated artificially? Yes. Is the process scientific? Yes. We can now answer in the affirmative.
Artificial rainfall generation is a deliberate act by man to alter or interfere with the water cycle. The cloud used is mainly the cumulonimbus cloud. This interference is aimed at increasing the amount, duration and density of rainfall in a particular region. It is also aimed at preventing drought in areas that are experiencing drought or areas prone to drought.
Every part of the hydrological cycle can be modified by man; the runoff water is now stored behind dams which can be used for several purposes including agricultural purpose, evaporation can be reduced by coating water surfaces with suitable chemicals like silver-iodide, transpiration losses can be reduced by removing pheatophyles. Ground water can be recharged by water spreading and pumping and river flows can be diverted.
In the same way, region rainfall can be generated artificially under suitable conditions although the amount to be generated cannot be predicted exactly at the present state of knowledge because regional climate differ around the world. The tropical regions will tend to produce more rain than the humid and desert regions.
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Artificial rainfall technique can be used to greatly increase the annual rainfall of these American cities. Source JPL, NASA. NASA image policy
Artificial rainfall generated is focused not only in increasing rainfall amount in dry areas or in causing rains to occur but also in decreasing rainfall in areas that experiences excessive rain storms. The process is also scientific and it has been carried out in several regions including the tropical regions. The branch of hydrology that is concerned with artificial rainfall generation is hydro-meteorology
Rationale for Artificial Rainfall Generation
Basically, the need for artificial rainfall generation are summarized as follows;
- Artificial rainfall generation helps to increase precipitation.
- Artificial rainfall generation helps to mitigate and prevent crop failure by promoting agricultural production.
- Artificial rainfall helps plants to grow, increase the level in reservoir irrigation water in so many regions and add water to the soil.
- Artificial rainfall generation also help in bringing the temperature of an area that has been experiencing excessive heat and the evaporation, to a bearable minimum, suitable for human life, animal and plant.
- Artificial rainfall generation can ease droughts; when plenty silver-iodide missiles are fired to alleviate the dry spells that have lasted for years.
- Artificial rainfall generation can be used to increase the water level of stream channels for the purpose of power generation.
- Artificial rainfall generation can be used by scientists to test new scientific technology or invention.
Approaches to Artificial rainfall Generation
Presently, there are two main approaches to artificial rainfall generation or three if the efforts of local “rainmakers” in Africa is added. These approaches are through cloud seeding and through temperature modification. These approaches are quite apart from the local inadvertent effects caused by large cities, large artificial lakes, and modification by vegetal cover.
THE CLOUD SEEDING APPROACH
The first and indeed the most popular scientific method of artificial rainfall generation currently, is however, the cloud seeding approach. Under this approach, the condensation of water vapor in the cloud is facilitated or enhanced through the introduction of condensation nuclei such as some air bourn particles such as dust or fragments of dry ice, addition of calcium chloride, addition of calcium carbide, and addition of calcium oxide into the clouds.
Also adding to the solution a compound salt and urea or alternatively a compound of urea and ammonium nitrate.
Condensation occur around these nuclei where the vapour is appropriate in the clouds and grows into water droplets. The droplets grow bigger and bigger until it becomes too heavy for the cloud to bear. Then it falls out of the solution as rain. Through this way, man can and frequently intervenes by supplying the suitable nuclei around which condensation can begin.
A cloud seeding artificial rain making approach. Image credit Wikimedia. Creative commons license. Author DooFi
Cloud seeding may also be carried out by burning of silver oxide, impregnated fuels or solutions at ground level to produce smoke which is carried upwards by wind into the upper air layers or effective zone. It can also be carried out by firing rockets containing condensation nuclei into effective zone or (more usually) by dropping the nuclei from aircrafts.
Clean air without such nuclei may become supersaturated or overladen with water vapor. In this way, man can and do intervene frequently in generating rainfall artificially by supplying the suitable nuclei around which condensation can begin. It should be pointed out, however, that this approach is useful only in clouds where the water vapour content is high enough and the temperature is low enough to be close to condition necessary for natural rainfall formation.
SURFACE TEMPERATURE MODIFICATION
The second approach to artificial rainfall generation is modification of the surface temperature of a desired location or region. This approach is more difficult and complex but it has the potential to increase rainfall amount. The basic preamble of this second approach is to re-examine the hydrological cycle of the region and then determine which parts of it should be modified. One area (or example) is the ocean surface from where most or a large portion of the moisture evaporate to form moist air masses.
a typical hydr ological cycle. Image source Wikimedia. Creative Commons Attribution-Share Alike 4.0 International license. Author Sunson08
A correlation relationship has been shown to exist between high temperatures over the pacific-ocean and rainfall falling on areas influenced by air masses moving over or through the ocean. A good example of such area is Sierra Nevada which is 800 miles west of the ocean and it experiences rain all year round. The exact areas of the ocean have also been delimited so if the conditions necessary for evaporation were optimized by scientists in these areas, more moisture would be available for rainfall and vice versa.
A modification of the temperature of such a surface (ocean surface) may impact on rain formation in the regions. A correlation, for example, has been shown to exist between high temperatures over the pacific-ocean and rainfall falling on areas influenced by air masses moving over or through the ocean
The third approach, that is the efforts of local efforts of local “rainmakers” have not been accepted by the scientific community due to a variety of reasons such as lack of transparency in the process adopted and not reliable because of its non-documentation of the method used.
STAGES IN ARTIFICIAL RAINFALL GENERATION
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cumulonimbus cloud. Source Wikimedia Creative Commons Attribution 2.0 Generic license. Contributed by Author
To carry out this process, the initial thing to do is to stimulate the air mass upwind of the target area to rise and form cumulonimbus clouds while the second stage is to increase the density of the clouds because the larger the density of the cloud, the more the rain. The third stage is to build up large beads of water and make them fall down as raindrops.
In executing these stages, a high level of expertise and experience is required in selecting the types and amounts of inputs (rain-making chemicals, aircrafts, etc.) to be used; and at the same time, taking into consideration the weather conditions of the region where the rainfall is needed, wind direction and velocity as well as the location or delimitation of the area for cloud seeding.
Problems associated with artificial rainfall generation
As promising as the field of artificial rainfall generation could be, it is not with problems and implications though recent researches are depopulating the list below, I will still pen them down as the problem encountered in the course of artificial rainfall generation. These problems may include:
- The conditions necessary and suitable for rainfall generation do not occur often in dry areas where extra rain water or rainfall is needed.
- Clouds with an abundance of natural nuclei or with above-freezing temperatures are not susceptible to rain-making.
- One cannot be absolutely certain that seeding is producing an actual increase in rainfall or just producing the normal amount of rainfall that would have naturally fallen.
- Once the clouds have been seeded, it is difficult to direct the rainfall to the required location.
- Seeding may produce more rain than was originally intended, this could result in floods, crop damage, erosion, soil slide, etc. They may lead to legal and social problems. Artificial stimulation of rainfall therefore offers little solution to the problems of water scarcity in arid and semi-arid areas.
- The excessive use of most of these chemical compounds used in the production of these rain could affect the climatic patterns, ecosystem, water sources and the soil. Excessive use of the chemicals would affect biodiversity and make the soil unproductive, besides being a water pollutant. The chemicals are most likely to affect the natural hydrological circle in the atmosphere.
- Again, experience in countries where the technology of artificial rainfall generation is in use, shows that the outcomes has been disastrous. China for instance, which invested massively in artificial rainfall generation technology, was recently a victim of Bird flu that killed human beings and birds.
- Finally, there is the problem of high cost. The technology of artificial rainfall generation requires heavy financial outlay – to fund researches, purchase equipment, among other things.
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chemicals used in artificial rain making have long term effect on the ecosystem. Source credit: wikimedia Creative Commons Attribution-ShareAlike 3.0 License. Author Smcnab386
CONCLUSION
Scientists now agree that artificial rainfall is feasible and that where there is enough water vapour in the cloud, seeding can increase precipitation amount considerably. Experiments are on-going in several countries such as Australia, China, South Africa, India, United States of America, Canada, etc. Increased rainfall generation is needed in many regions as it would greatly promote development in the agricultural sector, industries and in the domestic sector as well. However, artificial rainfall generation is associated with so many problems which were discussed herein.