Cloud seeding, also known as weather modification, is the attempt to change the amount or type of precipitation that falls out of clouds, or their structure, by dispersing substances into the air which serve as cloud condensation nuclei and aid in the formation of precipitation. The most common chemicals used for cloud seeding include silver iodide and dry ice (frozen carbon dioxide).
Seeding of clouds requires that they contain supercooled water--that is, liquid water colder than zero Celsius. Introduction of a substance, such as silver iodide, that has a crystalline structure similar to that of ice will induce freezing (heterogeneous nucleation).
In mid-latitude clouds, the usual seeding strategy has been based upon the vapor pressure being lower over water than over ice. When ice particles form in supercooled clouds, they grow at the expense of liquid droplets and become heavy enough to fall as rain from clouds that otherwise would produce none.
Seeding of tropical cumuli sought to exploit the latent heat released by freezing as well. This strategy of "dynamic seeding" assumed that the additional latent heat would add buoyancy, strengthen the updrafts, ensure more low-level convergence, and ultimately cause explosive growth of properly selected cumuli.
Cloud seeding chemicals may be dispersed by aircraft or by dispersion devices located on the ground. For release by aircraft, silver iodide flares are ignited and dispersed as an aircraft flies through a cloud. When released by devices on the ground, the fine particles are pulled further up into the air by the air currents after release.
While cloud seeding has shown to be effective in reducing the amount of cloud cover, it is more controversial whether cloud seeding increases the amount of precipitation from a cloud. Part of the problem is that it is presently impossible to know how much precipitation would have occurred had the cloud not been "seeded".
The National Center for Atmospheric Research (NCAR), an institution in Boulder, Colorado, has made some statistical analysis of seeded and unseeded clouds trying to understand the differences between them. They have conducted seeding research in several countries that include Mexico, South Africa, Thailand, Italy, and Argentina.
[edit] History
One scientist associated with the invention of cloud seeding is Irving Langmuir. The first attempt at cloud seeding was in Massachusetts in 1946. A plane "seeded" a cloud with crushed dry ice and snow began falling out of that cloud. Noted atmospheric scientist Bernard Vonnegut (brother of novelist Kurt Vonnegut) is credited with discovering the potential of silver iodide for use in cloud seeding. This property is related to a good match in lattice constant between the two types of crystal (the crystallography of ice later played a role in Kurt Vonnegut's novel Cat's Cradle). It is important to mention that silver iodide is mostly used for hail suppression while the new technique called hygroscopic seeding is used for the enhancement of rainfall in warm clouds.
One private organization which offered, during the 1970s, to conduct weather modification (cloud seeding from the ground using silver iodide flares) was Irving P. Crick and Associates of Palm Springs, California. They were contracted by the Oklahoma State University in 1972 to conduct such a seeding project to increase warm cloud rainfall in the Lake Carl Blackwell watershed. That lake was, at that time (1972-73), the primary water supply for Stillwater, Oklahoma and was dangerously low. The project did not operate for a long enough time to show statistically any change from natural variations. However, at the same time, seeding operations have been ongoing in California since 1948.
An attempt by the United States military to modify hurricanes in the Atlantic basin using cloud seeding in the 1960s was called Project Stormfury. Only a few hurricanes were tested with cloud seeding because of the strict rules that were set by the scientists of the project. It was unclear whether the project was successful; hurricanes appeared to change in structure slightly, but only temporarily. The fear that cloud seeding could potentially change the course or power of hurricanes and negatively affect people in the storm's path stopped the project.
In Australia, CSIRO conducted major trials between 1947 and the early 1960s:
1947 – 1952: CSIRO scientists dropped dry ice into the tops of cumulus clouds. The method worked reliably with clouds that were very cold, producing rain that would not have otherwise fallen.
1953 – 1956: CSIRO carried out similar trials South Australia, Queensland and other States. Experiments used both ground-based and airborne silver iodide generators.
Late 1950s and early 1960s: Cloud seeding in the Snowy Mountains, on the Cape York Peninsula in Queensland, in the New England district of New South Wales, and in the Warragamba catchment area west of Sydney.
Only the trial conducted in the Snowy Mountains produced statistically significant rainfall increases over the entire experiment.
[edit] Modern uses
The largest cloud seeding system in the world is that of the People's Republic of China, which believes that it increases the amount of rain over several increasingly arid regions, including its capital city, Beijing, by firing silver iodide rockets into the sky where rain is desired. There is even political strife caused by neighboring regions which accuse each other of "stealing rain" using cloud seeding[1].
In the United States, cloud seeding is used to increase precipitation in areas experiencing drought, to reduce the size of hailstones that form in thunderstorms, and to reduce the amount of fog in and around airports. Cloud seeding is also occasionally used by major ski resorts to induce snow fall. In January 2006, an $8.8 million cloud seeding project began in Wyoming to examine the effects of cloud seeding on snowfall over Wyoming's Medicine Bow, Sierra Madre, and Wind River mountain ranges. [2]
A number of commercial companies, such as Aero Systems Incorporated [3], Atmospherics Incorporated [4], North American Weather Consultants [5] and Weather Modification Incorporated [6] offer weather modification service centered around cloud seeding, and the USAF proposed its use on the battlefield in 1996.
In Australia, CSIRO’s activities in Tasmania in the 1960s were successful. Seeding over the Hydro-Electricity Commission catchment area on the Central Plateau achieved rainfall increases as high as 30% in autumn. The Tasmanian experiments were so successful that the Commission has regularly undertaken seeding ever since in mountainous parts of the State.
Beginning in Winter 2004, Snowy Hydro Limited is conducting a six-year research project of winter cloud seeding to assess the feasibility of increasing snow precipitation in the Snowy Mountains in Australia. At the July 2006 G8 Summit, President Putin commented that air force jets had been deployed to seed incoming clouds so they rained over Finland. However, not much seemed to come of this as there was torrential rain at the St Petersburg site during the summit meeting [7]
In Southeast Asia, open burning produces haze that pollutes the regional environmental. Cloud-seeding has been used to improve the air quality to encourage rainfall
2006-11-09 03:36:06
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answer #1
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answered by bb 3
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St Petersburg has a thing that gets below the skin and if you wish to find what it's then, you need to have a look with hotelbye . Nevsky Prospect is St Petersburg's main avenue and one of many best-known roads in Russia. Cutting through the traditional heart of the city, it operates from the Admiralty, image of Russian power, to the Alexander Nevsky Monastery and it will be really beautiful to go along that block at night when all illuminations on. Here, you can see every thing: probably the most spectacular architecture, the spectacular palaces, the world-famous museums and the shining five-star hotels. One of the places must see from St. Petersburg is State Hermitage Museum. The main architectural collection of the Hermitage is situated in the middle of St Petersburg and consists in: Winter Palace, once the former state residence of the Russian emperors, buildings of the Small, Old (Great) and New Hermitages, the Hermitage Theatre and the Auxiliary House.
2016-12-20 02:35:26
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answer #2
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answered by Anonymous
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The purpose is to create a surface that will reflect solar radiation, instead of the ground absorbing it.
The planet has been losing polar ice at an exponential rate, and if it were to continue and all melt then we would see major consequences. By creating large blankets of clouds, the idea is to reflect enough solar radiation back into space in order to cool the planet.
The trails are composed of different mixes. Generally, the trails will expand to make a solid blanket or covering. They do not make isolated puffy cloud formations.
Aluminum and barium are the two major elements being used. Silver iodide has been used for a long time, but it is not as controllable.
When aluminum nano particles are dispersed, and meet with the slightest moisture in the air, the nano aluminum begins to react, or oxidize, with a significant thermal change. Basically, aluminum dust is sprinkled into the air, and the dust heats up very quickly, giving off steam. The steam continues to build up and forms a haze of moisture.
When the aluminum is combined with barium, you have an opposite thermal reaction. The two elements get VERY cold. So when you combine the ability to create streams of hot air and streams of cold air, you now have opposite forces in which to control the clouds.
Additionally, electromagnetic frequencies are emitted into the atmosphere that stimulate the particles. This can simply keep the particles afloat, or walls of varying temperature can be made to contain, steer / direct, or deflect artificial or natural fronts. Clouds targeted with frequency can be seen in the sky having a consistent ripple look to them. Usually the ripples are uniform and tight, and can be seen on the edges of the blanket clouds (after the trails spread).
Modern cell towers are everywhere these days. They are capable of more than providing cell phone service.
2014-03-11 07:58:34
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answer #3
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answered by Patrick 1
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Perhaps you are talking about some images about war in Afghanistan in witch were visible large white circles in the sky caused by AC-130 "Spectre" Gunships.
These airplanes are armed with some guns (usually2x20mm, 1x40mm, 1x105mm) firing from one side of the fuselage, so they are equipped with an automatic system that make the airplane "orbit" around the target in order to have a lot of time to open fire and hit the target.
2006-11-07 23:12:12
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answer #4
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answered by sparviero 6
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i'm uncertain. i do no longer likely observe the persons/their age in top quality. perchance they're claustrophobic, in a rush (so as that they must be on the brink of the front), had extra miles, etc. a million. have you ever flown top quality? (I in basic terms have been given to for the reason that they had overbooked financial equipment! i've got by no skill paid for it) -i think of a pair of times because of the fact of a few reward. 2. How previous have been you once you flew for the 1st time? -i think of three-4. My mom's from the Philippines so we circulate there each few years. 3. have you ever flown by skill of your self? -Yup. 4. the place have you ever flown on my own in case you have? -At 18 some circumstances around the state to family members's domicile. At 20 to eire to circulate to a college there for the summer time. 5. what's the longest flight you have ever had? -sixteen hours. 6. what's the final flight? Aer Lingus 7. what's the worst flight? Uh. Southwest? i'm uncertain. i've got not incredibly had a terrible flight. 8. What do you generally do once you're flying to no longer be bored? -study a e book, hear to music, watch a action picture. 9. What do you placed on? -I generally placed on a sweater/denims because of the fact i like to stay snug.
2016-11-27 20:17:46
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answer #5
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answered by ? 4
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Making clouds??? Some are crop dusters, and some are show planes. If your talking aobut them straight lined clouds, then its a jet going at a certain altitude to where it shows their exhaust.
2006-11-05 04:36:42
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answer #6
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answered by Silverstang 7
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Making clouds? Well I dont know of any cloud making planes and I have heard of chem trails though what do you mean?
2006-11-05 10:01:17
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answer #7
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answered by shawn_mauldin 2
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I think you may be talking about contrails. A contrail is created because the exhaust from the engine is at a very high heat and it mixes with the cold air at high altitudes and creates what looks like clouds.
2006-11-06 01:50:24
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answer #8
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answered by ? 7
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Are you wondering how to downoad for free Rise of Nations Rise of Legends? You can get it for free here: http://bitly.com/1qXIp9b
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2014-09-16 00:32:45
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answer #9
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answered by Anonymous
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Those planes are just flying so high that the temperature is colder and thinner and the exhaust shows.
2006-11-06 14:11:48
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answer #10
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answered by Jaws 1
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It is usually for aircraft show, or pylon attack= it means to scare you opponent in a dog fight from behind when you don't have ammunition's and your radar is off so you are not in visual
2006-11-05 05:37:27
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answer #11
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answered by Anonymous
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