visual ray wizard
Joined: 09 Jul 2005
Posts: 433
Location: United States |
Seeding clouds to prevent or minimize hail
 Tue Jun 27, 2006 3:33 pm
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1. How does cloud seeding work?
Cumulus clouds–the billowy, cauliflower-shaped clouds often seen in Texas skies during much of the year–are important rain producers in every sector of the state. As the predominant cloud type during the warmest eight months of the year (March-October), cumulus (or convective) clouds are responsible for producing the bulk of rainwater given by the atmosphere in any given year in Texas. These towering cloud formations form from strong updrafts of warm, moist air into an atmosphere that is unstable. Intense daytime heating of the near-surface layer of air, or a wedge of cold air moving across the state (as a cold front), usually triggers the formation of convective clouds.
Not all cumulus clouds become rain producers. In fact, only a small percentage of them ever develop the capability to yield an appreciable amount of rainfall. Those convective clouds that do produce rainwater are often inefficient: For all the moisture they incorporate from below, only a tiny fraction of that moisture (as cloud droplets) is ever used to grow large raindrops, which ultimately fall to the ground as rainfall. This may be due to the fact that an insufficient number of ice particles exists within the cloud, thereby limiting the amount of cloud droplets that can coalesce to create raindrops. Or the clouds simply do not live long enough, on their own, to allow those tiny cloud droplets to collide enough times with neighboring droplets to yield larger drops–and eventually rainwater. Seeding is intended to introduce into the cloud many more of these ice crystals (also called cloud nuclei) to allow much more of the moisture supply within the cloud to be converted into rainwater.
If done in a timely way and properly, cloud seeding can assist the natural process in clouds by giving them enough "seeds" to make a meaningful number of large raindrops. If a lot of the growing convective cloud has pushed upwards above the freeze level, the bulk of the cloud water above that freeze level becomes supercooled (which is to say, the cloud droplets remain in liquid form and do not turn into ice). But those supercooled cloud droplets readily attach to an ice crystal (natural or artificial), converting the ice crystal into a tiny snowflake or graupel, which can quickly grow into a raindrop before the cloud begins to collapse.
Silver iodide is a favored seeding agent because its crystalline structure is nearly identical to the natural ice crystal. When placed in the upper portion of the growing convective cloud rich with supercooled droplets, the silver iodide crystal can grow rapidly by tapping that vast field of available moisture. Indeed, because the vapor pressure gradient over ice is less than that over water, an ice crystal such as silver iodide will more readily attract the tiny cloud droplets than those droplets will collide with each other. In a matter of moments, the ice crystal is transformed into a large raindrop which is heavy enough to fall through the cloud mass as a rain shaft.
The silver iodide particles (nuclei) are sometimes released from
http://www.license.state.tx.us/weather/weatherfaq.htm
http://www.license.state.tx.us/weather/summary.htm
I think it is pretty obvious we need to have a national weather control program that takes into account the needs of all States so that no individual state manipulates the weather to their own benefit but cuts off rain flow patterns to those states downwind of their operations.
It needs to be coordinated on a national scale or else we will eventually fall into the same trap China has fallen into with neighboring regions accusing each other of stealing the other's rain.
http://www.google.com/search?hl=en&q=chinese+cities+fight+over+rain
The other thing to consider is that if an agency interferes with the natural process mother nature provides to bring balance to the environment, then we have to look at how forcing storms to artificially "rain out" might exaggerate droughts down wind of such operations.
From the look of this map our grain belt is in serious trouble and the hard working farmers in these regions must be suffering terribly. Weather control has only been around for about 60 years but from the looks of this we still have alot to learn about how to interact with nature in ways where we don't cause undesirable results.
Another thing to consider is that big farming corporations might be trying to drive individual farmers out of business. Google weather derivates and you will find that weather can be controlled for a price. It is a multi billion dollar business and those who have deep pockets can have the weather tailored to their needs. Unfortunately we have no national oversight of such things so it leaves the entire process open for corruption in a very big way.
Take for example in the State of Wyoming where we have one region that is in the dark green while most of the rest of the state is in the brown to red. This is not normal and most likely we have some kind of weather control operation going on to the detriment of the surrounding regions. It's just a theory but one worth discussing especially since we have pending legislation in Congress.
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Being one with nature never felt so good! |
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