Few people can appreciate the complexity of the field of weather modification. How does one develop a "test environment" to compare the results of weather modification experiments to? How does a scientist prove that weather modification is possible, by proving it wrong? Intentionally or otherwise, mankind is modifying the atmospheric environment. Early attempts of weather modification in a nutshell were just prayers by farmers praying for rain or praying that the rain would stop. Then came World War II and self-centered military applications of weather modification were realized they needed to land the planes anywhere at any time. So the United States military has modified the weather. If the weather was in their way they would fix it, after all if they could split an atom they could surely fix the weather. Today we know a lot more about the complications in meteorological processes than we did during World War II. We now have meteorologists armed with very sophisticated computer systems to measure, record and analyze in great detail the complex system of the weather. Are ordinary people currently involved in artificial means of weather modification? It is quite imperative that people become better informed in this whole area and start to measure the effects in the great detail required. It is quite clear that this subject of weather modification is going to have an impact on our lives, intentionally or accidental. Legislators are going to have to make important future decisions regarding the impact of weather modification. The pressures of world wide population increase make it clear that we are going to have to live with increasing controls. Man controlling the weather, via prevention of pollution in our atmosphere or regulating our climates for population accommodation, both are inevitable!
Why change the weather with weather modification, why not? The military has been playing around with the weather since World War II. A much better reason to modify the weather is simple, down to earth, economics. Thousands perhaps millions of people world wide literally live or die each year depending on how the weather affects harvests. For example for wheat-raising farmers in the Pacific Northwest normal rainfall is about 7.5 inches per year. Each additional inch of rain annually would result in increased yield of about 3 1/2 bushes per acre. At today's prices on a 1,000 acre farm a 3 inch rainfall increase would net the farmer an additional one hundred thousand dollars in income. Agriculture precipitation augmentation, via weather modification could conceivably provide more food to the worldwide human food budget.
Fog has plagued mankind for centuries, shortly after WWII man did something about these low clouds. A fog-dispersal system called FIDO (Fog Investigations Dispersal Of) proved that the application of sufficient heat to the air could burn away fog and thus permit aircraft to land. A recent search of the United States Patent and Trademark Office website showed 19 U.S. Patents granted for warm and cold fog dissipation devices in the weather modification categories. It would make good economic sense to put cost effective fog dissipation devices to work at all major airports. NASA would also benefit from cloud dissipation devices because they would not have to delay costly space shuttle launches due to inclement weather. Those cloudy rainy days and launch delays costs NASA, and ultimately the U.S. taxpayers, millions of dollars per day, so the economics of weather modification makes good sense.
Clouds, you can see them and you can walk through them provided you are up in the mountains. The atmosphere around us contains variable amounts of water vapor. The amount of water vapor that can exist in a given volume increases as the temperature rises. Relative Humidity is a measure of the concentration of water vapor; it is the percentage of water vapor present relative to that which the air could hold. If a volume of air is cooled by lifting it to regions of lower pressure the relative humidity will rise. At 100% RH the air is then said to be saturated, if further cooling takes place the excess water vapor will condense into cloud droplets that you can see. Then you can see what we all know as a cloud.
Cloud droplets can form around cloud condensation nuclei (CCN). The atmosphere contains an abundance of hygroscopic aerosol particles, which attract water vapor. These particles are most apt to serve as CCN. The result of the abundance of CCN combined with air at saturation produces clouds containing small water droplets in high concentrations. These resulting water droplets are so small that it takes a million of them to make a single raindrop. Up to one hundred million of these small water droplets may exist in one cubic meter. So a small cumulus cloud that you see contains trillions of tiny droplets.
There are aerosol particles, called freezing nuclei, in the atmosphere which cause cloud droplets to freeze or ice crystals to form directly from water vapor. These particles whose molecular structure are similar to the structure of ice are relatively scarce, so most cloud droplets remain in the liquid state below 0*C. Such water droplets are said to be supercooled. Supercooled water droplets can remain liquid to temperatures of -39*C, at the temperature of -40*C all water droplets freeze. At about -10*C freezing nuclei allow for the cloud droplets to freeze around them. So, ice crystals and supercooled water droplets can exist within a cloud at the same time. When you have these conditions: air that is saturated, supercooled water and ice crystals within a cloud a natural cloud process called the "Bergeron Process" kicks in. What happens (according to Mr. Supercooled Water Droplet) is the air and the supercooled water droplets are in equilibrium at saturation (100%). But the air according to the ice crystal is supersaturated (> 100%). Therefore the water vapor in the air will sublimate on the ice crystal at the expense of the supercooled water droplet, which will evaporate to compensate for the loss of water vapor. This cycle continues feeding on itself (latent heat is released) and the cloud grows.
It is possible that natural cloud processes, such as the formation of precipitation can be modified by seeding clouds with the appropriate types and numbers of nuclei at the proper times and places. Seeding with ice nuclei, such as silver iodide particles, (The threshold temperature below which silver iodide is an effective ice nucleant is -4*C) can supply clouds with additional ice particles and thus increase the efficiency of the "Bergeron Process". The nucleating ability of silver iodide increases as the temperature falls. The silver iodide is released from devices called liquid fuel generators, or pyrotechnic flares which can produce as many as 1,000,000,000,000,000 particles from 1 gram of silver iodide.
One of the tasks of early magicians was the creation of rain by a variety of methods from the smearing of witchdoctors with blood and chicken feathers to burning sacrificial fires and staging of rain dances. The Indians practiced an assortment of rainmaking rituals. They smoked special pipes, burned tobacco by the stack. and shot arrows at the clouds-perhaps to spear the rain out of them. The Indians prayed, danced, and chanted. The Choctaws hung a fish around a tribesman's neck and stood him in the nearest stream until either it rained or somebody in authority came up with a good explanation of why it didn't.
The modern types of weather modification with intended precipitation increase are cloud seeding with dry ice and silver iodide. Important discoveries in 1946 at the General Electric Laboratories in New York, has led to practical methods for modifying large volumes of clouds at a reasonable cost. Vincent Schaefer of GE seeded a cloud with a few pounds of dry ice and caused snow to fall. A few years later, Dr. Irving Langmuir a GE scientist and Nobel Prize winner, claimed that he caused a hurricane to swerve from it original path. He continued on until his death in 1957 with numerous weather modification experiments involving both dry ice and silver iodide. Vincent Schaefer & Dr. Langmuir are also credited in discovering the critical temperature of -40*C, the temperature at which supercooled water droplets freeze.
Both scientists Dr. Irving Langmuir and Vincent Schaefer were passionate mountaineers. Their interest in meteorology started during the ascent on foot to the observatory on Mount Washington in New Hampshire during the wintertime of 1946. They were both surprised to notice that the clouds/fog at the top of the mountain consisted of fine mist like water droplets. They were hiking at the top of the mountain (1,919 meters) in temperatures far below 0*C and they noticed that the ("supercooled") droplets deposited rime on solid objects, but did not freeze in the air but remained liquid. Schaefer then went back to the labs at GE and then came up with a simple experiment, to test what they had noticed up on the mountain. By breathing into a deep-freeze box, he produced clouds: a perfect copy of natural conditions. The moisture in his breath condensed into fine mist droplets, but no ice crystals formed, and the temperature inside the box was below -20*C. The mist remained in the box for about 10 minutes then deposited as rime on the walls of the box, supercool experiment! Then Schaefer decided to induce the formation of ice crystals within the box. He tried different substances soot, volcanic ash, graphite, and sulpher all without success. Then after hundreds of failed experiments the temperature in the box increased, due to a hot July day, and he decided to put some dry ice into the box to cool it down. The moment it made contact with the "supercooled" water droplets, thousands of small snowflakes formed. A tiny piece of dry ice (frozen carbon dioxide) was sufficient to produce this reaction. He soon realized that the triggering factor was the low temperature a critical temperature of -40*C. When the moist air entered the box, which had been cooled below this temperature, ice crystals formed immediately, without any additives. The crystals that formed looked exactly like natural snowflakes.
Schaefer then told Langmuir of his experiments and Langmuir realized what had been achieved in the box could also be done in nature. Man had figured out a process that made it possible to change clouds at will and to induce precipitation. On November 13th, 1946, Schaefer carried out the first test. From an aircraft he sprinkled three pounds of finely ground dry ice onto a supercooled stratus cloud deck. In less than five minutes snowflakes formed and fell 1,000 meters before evaporating. A large hole had also opened up in the cloud deck where the dry ice had made contact with the cloud. More tests followed and just to be sure dry ice was dropped in the pattern of the General Electric Logo over another stratus cloud. From the ground newspaper reporters saw the GE logo cut out of the cloud above and the news made the front-page headlines the next day. Langmuir was quoted that applications of techniques of this kind would soon enable man to change the weather at will.
This new discovery caught the attention of farmers, governments, and the U.S. Military. An associate of Schaefer's, Bernard Vonnegut, an icing nuclei expert, also became involved with further experiments. Vonnegut had been working on the study of aircraft icing and collaborated with Schaefer to find a nucleus particle with a structural shape suitable to induce ice formation. After looking through a manual on X-ray crystallography he found what he was looking for, silver. Silver iodide, because the atoms in a silver iodide crystal are very similar to that of an ice crystal. Both scientists worked on several experiments that failed, they worked with silver iodide, iodoform and pure iodine. Then they hit the jackpot with the following experiment. Vonnegut was working with the original deep freeze box, introduced moisture into the box, conditions similar to Schaefers "supercool" experiment. Vonnegut intended to try out the effect of metal-dust aerosols, which he generated with sparks between electrodes. He used an ordinary silver coin for the metal dust generator. He suspended the silver coin within the box between two electrodes and then turned on the electricity. The box was instantly filled with ice crystals. Soon after he established that silver iodide of sufficient purity produces snowflakes from "supercooled" water droplets at a temperature of -4*C. Vonnegut's new discovery, cloud seeding with silver iodide generators, prompted Dr. Langmuir to talk to some of his buddies in the U.S. military. "Project Cirrus" was conceived, via contract, in 1947 by the following U.S. interests, GE, Army Signal Corps, Office of Naval Research, Air Force, and the Weather Bureau. This was the first major scale scientific experimental project in the field of weather modification.
Project "Stormfury" was the next major scientific study; the project goal was to modify hurricanes over the Atlantic Ocean. Project "Stormfury" started in 1961 at Cambridge Research lab at Hanscom Air base in Massachusetts, the lab directors reported to The U.S. Joints Chief of Staff and the CIA. The U.S. Naval Weapon Center at China Lake developed special rockets; silver iodide generators called "The Alecto's" to provide the possibility of seeding hurricanes with adequate amounts of silver iodide. Hurricane "Debbie" in August of 1969 was the first hurricane to be seeded with the special rockets.
Weather modification has continued into the present day. Hail suppression, with an intended precipitation decrease includes the introduction of silver iodide (via aircraft shooting rockets) into the top of large towering cumulonimbus clouds. Several commercial worldwide companies are presently doing this type of work. The theory goes like this; the additional freezing nuclei (silver iodide) would result in higher ice particle concentrations that increase the competition for the available supercooled water droplets within the cloud. As a result, the hailstones that would normally develop may not grow as large as they would if the clouds were left unseeded. Weather modification companies such are presently involved in contract cloud/fog dissipation, cloud seeding (via aircraft) with crushed dry ice pellets. The ice pellets cut long rectangular holes through stratus clouds above airport runways. What can we expect in the future in regards to changing the weather? Mankind has always had a desire to change his surroundings, including the weather. Weather modification is destined to become a recognized science, because sooner or later someone will discover and develop a new device and solve weathers associated negative issues. The forests influence the atmospheric environment in a variety of ways. Since the beginning of agriculture, mankind has been spreading out and growing in population at the cost of large amounts of forest. Most of the presently cultivated areas, fields harvested by farmers, were once covered with forests. It is reasonable to say that mankind has altered or modified the climate by removing most of the forests in the world over time. It may not be possible to determine which changes in the weather are caused by natural climatic fluctuations and which ones are caused by human intervention. But there is no doubt that forest clearing and overgrazing have intensified desert growth and enlarged arid regions in the world. The growth of urban areas and the "industrialization" of the world are also effecting or modifying the atmospheric environment. The metropolises of the world are nothing more than giant "heat islands" with overall temperatures higher than that of their surrounding environment. The hydrologic cycle has no doubt been effected by man, the damming of rivers create artificial lakes where they do not belong. The Hoover Dam placed in the middle of the desert is a man-made redistribution of water that God and nature never intended. What does that do to the local climate surrounding the Hoover Dam, does not the water evaporate into the air and modify the humidity in the area?
The National Science foundation released a report in 1966 labeling environment tampering as dangerous on a par with global world war. According to a Material Safety Data Sheet on Silver Iodide, cloud seeding is relatively safe for the environment. Silver iodide possesses the chemical nature of inorganic salt, which is considered relatively non-toxic. However, heating the substance to decomposition may produce corrosive fumes of Hydrogen iodide. The substance is considered explosive when combined with Sodium and Potassium. As long as reasonable care is exercised cloud seeding with Silver iodide appears to be safe for the environment. In general there are two inherent dangers in weather modification: legal difficulties, and actual harmful effects resulting from changing the weather. A conflict arises when one group or local stands to benefit from weather modification and another to lose. There is a possibility of conflicts between groups seeking to modify the weather for different purposes or for the benefit of different areas. If I make it rain on my farm and you suffer a drought some distance downwind of me, can you sue me for stealing your precipitation? Or for flooding on your property. The laws in this country regarding weather modification differ from state to state with some states banning any weather modification activities. Currently 32 states have enacted legislation dealing with weather modification. Most states allow the practice of weather modification with a modest licensing fee. For example, the law in the state of Texas is as follows. The Texas Department of Licensing and Regulation, Weather Modification Law. In accordance with the rules adopted under this article, shall issue a weather modification license each applicant who pays the license fee of and demonstrates, to the satisfaction of the department, competence in the field of meteorology that is reasonably necessary to engage in weather modification and control activities.
It has been established and accepted in the United States that man under various circumstances can modify the weather. The problem is one of stating under what conditions predictable results may be expected. The design of a weather modification program to achieve a specified goal would be a good first step. Second the execution of the program utilizing the current state of the art. Then a comprehensive final analysis assessing the effects of the weather modification effort. Most important the effort must be for the good of mankind, perhaps the farmer, not for military superiority. To quote my favorite scientist Albert Einstein, "Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius -- and a lot more courage -- to move in the opposite direction." I once told a good friend of mine about my interest in modifying the weather. I was describing my involvement in a cloud dissipation experiment. My friend Herb interrupted me and said, "You can't do that! Your playing around with something that God wouldn't approve of." I was speechless, I thought about what he said for a very long time. My experiment, my curiosity, it is not about God it is about science. Albert had said the same thing many years before I was born, "Science without religion is lame. Religion without science is blind."
