4
$\begingroup$

This article lists several mechanisms that may be used to control the weather and/or induce rainfall. Apparently many states, other than the one listed in the headline, have experimented with such techniques. The article also lists concerns over contamination from such artificial rainfall.

Say I, a layman without access to a laboratory, collect the rain in a glass. What test/tests may I apply to determine whether it is natural rainfall, or the outcome of cloud seeding?

$\endgroup$
  • 4
    $\begingroup$ It would be totally impractical to do such testings. The "contamination" levels would be much too low to be detected. You have to realize that air isn't pure. When a raindrop falls it would wash out all kinds of gunk that was in the air. $\endgroup$ – MaxW Jun 21 '16 at 6:35
  • 6
    $\begingroup$ True, air and water are not pure anyway, but silver iodide is usually not a natural contaminant; a well-equipped laboratory may be able to detect it. A layman might just as well sit down and pray. $\endgroup$ – Ivan Neretin Jun 21 '16 at 7:24
  • $\begingroup$ Could it be tested obliquely? Does the presence of silver iodide imbue water with any features/properties that would not normally be there? $\endgroup$ – Everyone Jun 23 '16 at 10:16
  • 4
    $\begingroup$ While extensive lab measurements have been conducted to measure "seed" concentrations, as @MaxW commented the levels are just too low and methodologies too complex for routine home measurements. As one example of background concentration problems, in the US only about 1% of the atmospheric emissions of silver come from cloud seeding. $\endgroup$ – airhuff Jan 29 '17 at 1:17
1
$\begingroup$

The AgI would act as a cloud condensation nuclei (CCN) on which water vapour would condense allowing cloud droplet formation. Presumably, you could use scanning electron microscopy to determine the composition of the CCN and determine whether cloud seeding has taken place.

Apparently, his has already been done with cloud chamber (so, artificial scenario) measurements (Zimmerman et al., 2007 - "Environmental scanning electron microscopy (ESEM) as a new technique to determine the ice nucleation capability of individual atmospheric aerosol particles").

However, considering that there has been ESEM measurements in field situations before (Pöschl et al., 2010 - "Rainforest Aerosols as Biogenic Nuclei of Clouds and Precipitation in the Amazon") to determine CCN composition, I suppose a similar set up could be performed.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.