Tale srebrov jodid je zelo zdrav drgač, tako je ugotovila Weather Modification Association (WMA) leta 2009. Seveda razen na wayback machine tega ni nikjer več. Čudno ne, sej gre ja za zdrave kemikalije.
Silver iodide is usually sold by commercial chemical company distributors in granular or
powder form. It is used in combination with various other chemicals, most often salts, and has
been used for half a century as a glaciogenic agent (microscopic sized particles, referred to as ice
nuclei, ice forming nuclei, or occasionally freezing nuclei, that spawn ice crystal formation).
Silver Iodide is considered water insoluble (solubility constant at 10-9
g[of Ag] g
[of solventwater]; see units note), which means that if one gram of the chemical is added to one gram of
water, roughly one billionth of that gram of silver iodide would dissolve in to the water; the
remainder will stay in the water undissolved. This property allows the silver iodide particles to
maintain their structure prior to contact with supercooled (colder than freezing) cloud droplets.
Silver iodide, as used in cloud seeding, is either dissolved in a flammable solution or combined
with other flammable solids to produce seeding flares or other devices, which are burned to
release submicron-sized, virtually invisible, silver iodide aerosol complexes into the atmosphere.
These complexes are plentiful in number and increase the probability of ice crystals forming
when they reach cloud environments at temperatures near or colder than the AgI ice nucleation
(or crystallization) temperature threshold (about -5°C). This is significantly warmer than the
threshold of most naturally occurring ice-forming nuclei, which commonly have thresholds near -
15°C and colder.
Only small quantities of seeding material are released from individual cloud seeding
generators typically in the range of 5-25 grams of silver iodide per hour from ground generators
and up to a few kilograms per hour from aircraft depending on the size of the target area.
Moreover, this is being done only during certain periods and locations of precipitation-producing
weather systems. The reason that such small quantities can be used is that AgI dispensing
systems generally produce up to 1015 (see power of 10’s note) ice forming nuclei per gram of AgI
expended (e.g., ASCE 2004, 2006). This means small amounts of AgI seeding material can
produce tremendous numbers of ice crystal seeds that can create ice crystals, which can grow into
snowflakes. The insolubility of AgI is a crucial factor for such small particles that allows them to
maintain their identity (structure) intact and not condense water (and thus lose their structure)
inside a cloud droplet. Without this property there would be no cloud seeding effect.
As a metric of cloud seeding chemicals, silver concentrations have been measured in the
snowpack of several cloud seeding target areas in the western U. S. The average concentrations
throughout the snowpack have generally ranged from 4-20 x 10-12
g[of Ag] g
rarely exceeding 100.0 x 10-12
(Warburton et al. 1995a,b, 1996; McGurty 1999). Since
seeding clouds could lead to rain (if snowflakes melt during their fall to earth) measurements of
seeding chemical concentrations in the rainwater have also been done and found to be in similarly
low concentrations (e.g., Sanchez et al. 1999).
Urejal voith, 03.10.2022, 11:18.