Several attempts have been made by various researchers to create artificial rain by laser. Golde [1], from a number of radar observations, has reported that intense precipitation is not even present in the clouds before the first discharge but develops abruptly in the same region after discharge from which the lightning flashes originate. Carls and Brock [2] heated the atmosphere by a laser pulse up to 1600 to 2800 K and observed water droplet formation. They predicted that high temperature causes ionization of N₂ and O₂ and, when this ionized air is subjected to more radiation, avalanche breakdown of air can occur. Braun et al. [3] have observed laser-induced condensation and water drop formation by shooting self-channeling of high-peak-power femtosecond laser pulses in the air. Yoshihara et al. [4] have shown that the pulsed UV-laser irradiation of ambient air induces the formation of water droplets or small ice particles in the laboratory. They also observed that [O] formed in this process quickly reacts with O₂ molecules to form O₃. Rohwetter et al. [5] have shown that ionized filament, generated by ultra-short wave laser pulses, induces water-cloud condensation in the sub-saturated atmosphere in the altitude region between 45 m and 75 m. A team, called terra-mobile-group (TMG), consisting of scientists from Switzerland, Germany, and France, has been trying to create artificial rain by laser [5-9].

 They have done simulation experiments in a laboratory cloud chamber and have observed condensation and water drop formation. They also succeeded in producing tiny water particles in moderately humid air at an altitude of 45 to 75 m in the atmosphere by terawatt mobile laser. But the droplets were about a hundred times too small to fall as raindrops; instead, they remained suspended in the air. The team feels that it is feasible to get larger droplets if the power of the laser is increased to petawatt (1015 watts) or exawatt (1018 watts). They further say that the effectiveness of this method is much easier to gauge than traditional cloud-seeding techniques and that it could provide a practical means of triggering rainfall”.  (See Google as “Laser makes rain, heavily, 2010”). A group of scientists from Florida University also observed water drop formation by high-power laser shooting experiment. It appears from the above that laser has not yet succeeded in producing artificial rain. In this paper, a novel method is described to create artificial rain by laser.

Condensation is the basic need for water drop formation. This can be understood by taking two glasses, one filled with normal water and another with ice pieces. After some time, one can observe water droplets on the outer surface of the glass that contains ice but not in the other. This is due to the condensation process that occurs around the ice glass due to low temperature. In this project a laser beam will be shot in the cloud region of the atmosphere to initiate endothermic reactions. As a result of these reactions, temperature drastically falls, condensation takes place, seeding occurs, and it rains in an analogous way as it rains after lightning.

How Will the Laser Create Artificial Rain? Theory

The methodology is to send a laser pulse to the cloud region of the atmosphere to create high temperature. This high temperature will break the bonds of O₂ and N₂ molecules as follows:

N₂ :  N ≡ N → N* + N   -----------    (1)

O₂ : O = O → O* + O   ------------   (2)

In this process N and O atoms in an excited state (N*, O*) will be created. These excited N* and O* will immediately convert to Ozone (O₃₎ and Nitric oxide (NO) through the following reactions.

N* + O₂ → NO + O ΔH (43.2 kcal/mole) -----------   (3)

O* + O₂ + M → O₃ + M ΔH (67.7 kcal/mole) ----------    (4)

The occurrence of reactions 3 and 4 and the formation of NO and O₃ have confirmation from NASA laboratory experiments [10]. Formation of O₃ and NO, after laser shot, has been observed in laser experiment in atmosphere [11]. The reactions 3 and 4 are endothermic and absorb a large amount of heat energy (amount mentioned in brackets) from the cloud region. As a result, the temperature of the cloud region drastically falls, condensation takes place, seeds (CCN) will be formed, and tiny water drops will be created. These tiny water drops will act as natural seeds to form raindrops. Ozone and nitric oxide, O₃ and NO (formed in reactions 3 and 4), will undergo further reaction to form HNO₃ particles and other nitrogen compounds, which will bind water molecules together to create water droplets. These water droplets again will act as natural seeds to form another set of rain drops. In the atmosphere, due to turbulence, small water drops coalesce and form big raindrops. In addition, ions N₂⁺ and O₂⁺  and electrons formed by cosmic rays can create complex hydrated heavy positive and negative ions.  HNO₃-(H₂O)_n (where the value of n could be as large as 50), which can also act as a seed to create rain. It has been shown earlier how much heat energy is absorbed by endothermic reactions from atmospheric clouds [12-16]. The energy required to break bonds of 1 molecule of N₂ and 1 molecule of O₂ is 2.25x10^-18 joules. A laser pulse of energy of 500 mJ can dissociate a column of N₂ and O₂ containing (~0.5/2.25-18) ~ 10¹⁷ molecules, which is much higher than the density in the atmosphere.

The laser system can be operated from the ground as well as from an aircraft.

When the Laser is operated from the Ground

For this project, IRRA Scientist Group proposes laser system of following specification: peta watt laser (1015watt), 800nm, 500mJ, 120fs and 10Hz.  When more than 50% to 65% humidity is present in the atmosphere, a laser beam will be shot into the atmosphere. The laser pulse has to propagate with almost high peak intensity over a distance of ~1 km. simultaneously, atmospheric parameters like humidity, temperature, wind velocity, etc. also have to be measured to maximize the operation. The laser pulse will initiate endothermic reactions. It will convert warm white clouds or any type of cloud into black rainy clouds by cooling the region, generating condensation, and starting a seeding process leading to heavy rainfall. It will cover an area of ~16 km². The estimated cost of the project for three years is ~9.02 Cr in Indian Rs. / 0.72 million US dollars.  It’s a one-time investment and can be used multiple times at any place. It may be mentioned here that in Vedshastra, an Indian religious book, there is a mention that special arrows sent towards the atmospheric clouds created rain.

Plans to operate the laser system from the ground are shown in figure 1. In this figure there are two lasers: a terawatt femtosecond Ti: sapphire pulse laser with a double coarse laser (1) primary laser and (2) secondary laser. In this system, secondary laser energy is used for laser pulse travelling purposes, and primary laser energy is used for creating artificial lightning in the upper atmosphere up to 1.2 km to 1.7 km altitude for the initiation of endothermic reactions. In this process a lot of heat energy is absorbed from the surrounding atmospheric clouds, the temperature drastically falls, condensation takes place, and water drops form in the atmosphere.

A laser system from ground level can be used in the field of farmers when the crops are on the verge of drying due to lack of rain.

For this experiment, a hilly area could be selected on the field of a farmer, with a high-power electric supply point already managed near the experiment site. The high-power laser system must be placed in a 12-wheel truck so that it becomes easy to transport it from one place to another.  When the upper atmosphere is cloudy and more than 65% humidity is present in the atmosphere, the experiment can be started. We will measure atmospheric parameters such as humidity, temperature, pressure, wind velocity, wind direction, etc. on ground level as well as in the upper level. For this purpose, a separate unit/department must be established as the “Measuring & Maintenance Department.” After the experiment, all data should be analyzed for maximum rainfall in the atmosphere. 

In this way laser system technology from Ground can be used for a green revolution for all human beings in the whole world.

Figure 1: Artificial Rainmaking by Laser System from Ground Level.

When Laser is operated from Aircraft/Drone

Laser can be operated from the ground as well as from an aircraft. In the former case, the laser pulse has to propagate to a height of ~1 km (cloud height) from the ground. There will be attenuation of energy in this propagation. So if a laser is operated from an aircraft or drone, a less powerful laser can be used. A laser beam will be sent from the aircraft to the cloud region to initiate endothermic reactions. The temperature of the cloud region will fall. Condensation will take place, and heavy rainfall will occur. It will work for any type of clouds in the atmosphere, and more than 50% to 65% humidity should be present in the atmosphere. It can cover an area of ~450 km². Operation using aircraft/drones will be more costly than operation from the ground. The estimated cost will be Rs. 230 Cr/US Dollar 28.75 million for three years. Simultaneously, atmospheric parameters like humidity, temperature, wind velocity, etc. also have to be measured to maximize the operation.

The project proposal, the design of the laser system, the budget estimate, and the work plan are ready with the IRRA Scientist Group. The IRRA scientist is ready for demonstration and collaboration with the government or any institution for funding or starting this project.

Flow Chart

1. A laser beam shot in the cloud region will create a very high temperature in that region.

              ↓

2. At this high temperature, bonds of N₂ and O₂ molecules of the atmosphere will break and excited N* and excited O* atoms will be formed as follows:

              N₂: N=N → N* + N,

              O₂: O=O → O* + O

These excited N* and excited O* atoms immediately undergo the following reactions:

             N* + O₂ + M → NO + O + M - ΔH (ΔH = 43.2 kcal/mole)

             O* + O₂ + M → O₃ + M - ΔH (ΔH = 67.7 kcal/mole) ↓

3. These reactions are endothermic and suck a large amount of heat (amount mentioned in brackets) from the surrounding atmospheric clouds.
4. As a result, the temperature of the region drastically falls, condensation takes place, seeds are formed and it rains (in an analogous way to how rain is created in nature by lightning).

Figure 2: For Rainmaking by Laser Using Aircraft in the Atmosphere.

Figure 3: Inner Design of “Position of Laser System in Aircraft”.

Note:

• In figure 2, on the first floor, height 9’, the shown parts (1), (2), and (3) are the high-power laser release system, which creates multiple artificial lightning in the upper atmospheric clouds directly by the laser system…
• In figure 2, on the second floor, height 7’ 6”, the shown parts (A), (B), (C), and (D) with the staircase are a high-power generation system for a high-power laser system, with railing for open space as shown by the square dots …..
• Our findings could be used by scientists and engineers to create artificial rain as a new method. The results could be of immense benefit to human beings as well as eco-friendly and cost-effective, which is the need of the hour.

This method can be used for rain harvesting by “rain drain.” When huge clouds are present above a lake or dam, a laser beam can be shot into the cloud region; then, with a blast of clouds, heavy rainfall will occur to fill the lake or dam for future use of water. This method can also be used to reduce pollution of the atmosphere by spraying artificial rain on the polluted city. Another use of this method is to stop excess rainfall. A low-intensity laser pulse shot into the cloud region will evaporate the clouds from the excess rainfall area. This method can also be used to drive away the rain cloud from the region where rain is not needed.

It is shown in this article that by initiating endothermic reactions in the cloud region of the atmosphere by a laser, artificial rain can be created. Laser can be operated from the ground or an aircraft. This method is economical (one-time investment), harmless, and eco-friendly and can be switched on and off when desired. It can be used at any place and at any time. It can also be used to fill a lake or dam for storing rainwater for future use (rain harvesting) or to reduce pollution by spraying artificial rain on the polluted city. Artificial rain will also help to increase the green life.

IRRA Scientist’s Aim: “The Green Revolution in the whole world for all human beings will be fulfilled.

Acknowledgement

We express our sincere thanks to: Prof Mamata R. Lanjewar (RTM University Nagpur), Prof A. P. Deshpande (Principal, Science College), Prof. Padmanabhan Murthy (J.N. University, New Delhi), Prof Umesh Kulshetra (J.N. University, New Delhi), Prof K. S. Korgaokar (Pune University, Pune), Dr. A.L. Agarwal (NEERI Nagpur), Dr. Nitin Saraf (B.D. Engineering College, Sewagram), Dr. K. M. Kharate, (GM Engineering College & Research Centre, Sheogao), Dr. Mrs. Sumanlatha Pandey, Mr. Shyam Ujjaninkar (Engineer), Mr. Bhola Katare, Bhandewadi, (Jay Shri Jaganatha Namo Namha), Dr Dipak Deshmukh,Shegao ,(Shri Gajanan Maharaj)Shegao, Mr.Vithal Wagh, Waigegao,Sadguru Parmhans  shri Ramchandra Maharaj Namo Nemaha. Mr. Rajesh Iyengar (P. N. College, Nanded). Dr. K.R. Gangakhedkar (P. N. College, Nanded). Ex. Prof. Ratnakar Lanjewar (HOD, Chemistry Department), Science College, Nagpur, Nanded, for their valuable suggestions and guidance for the project proposal.

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