High altitude dispersements

When dispersing things from high altitude such as seeds or chemicals whatever is there any mathematics involved in figuring out the type of pattern that can be expected? Or is it a matter of trial and error? Let’s just say 20 to 30,000 ft disbursements for example

There is an entire branch of fluid dynamics that addresses this area.

That being said, some of the more experienced crop-dusters in my area say that there is a certain amount of experience necessary to get the “spread” just right.

The emergence of GPS tracking has had a major influence on crop-dusting. It is amazing how all of the product can be tracked to what field it was applied to & how much was spread where.

I’ll note that:
disburse = pay out money from a fund
disperse = spread widely

Don’t tell the crop dusters this. I’m counting on their disbursements to augment my pension

Atmospheric dispersion modeling comes to mind, though this is usually about the dispersion of positively-buoyant aerosols or gas mixtures released at or near ground level (up to the height of industrial smokestacks):

https://en.wikipedia.org/wiki/Atmospheric_dispersion_modeling

A slide show you can flip through:
https://ansn.iaea.org/Common/Topics/OpenTopic.aspx?ID=13012

Presumably many of these concepts would also be applicable to high-altitude release of negatively-buoyant aerosols/gas mixtures (minus the terrain interactions).

All the aerial crop-dusting or crop-seeding activities I’ve ever witnessed were done at insanely low altitudes (above ground level). Who does that from high altitude?

Things like cloud-seeding would be done at high altitude, or perhaps distributing wide-dispersal mind-control potions.

Fun fact: The practice of cloud-seeding was developed by, in part, meteorologist Bernard Vonnegut, brother of Kurt.

What I was actually thinking of the situation where you might be using powdered fertilizers but in extremely low concentrations spread out over very large areas

What fertilizers are effective in extremely low concentrations?

There’s quite a bit of research going on with this right now and they’re not talking about fertilizing like you would a farm just talking about supplementing already poor soil. The carbon fertilization has thrown the carbon nitrogen cycle out of whack. A lot of the research suggest that there is something you might be able to do about that

Aerial application of agricultural chemicals results in uneven distribution (google “gaussian plume”), as well as drift (due to ambient winds) of the chemicals away from the target. The higher the release, the worse these problems become. According to Wikipedia, many countries restrict or ban the practice.

The emphasis these days is on using chemicals as efficiently as possible, for cost and environmental reasons. Example, I recently saw a video where a tractor equipped with machine learning was able to visually distinguish between crop plants and weeds, and spray herbicide only on the weeds, resulting in less runoff and less cost. For fertilizer and other chemicals, farmers can similarly monitor soil and crop properties throughout their fields and apply these chemicals in differing amounts throughout their fields as needed, minimizing waste. Aerial application (even from low altitude) pretty much moves in the opposite direction, and anything released from 20-30,000 feet, as suggested in your OP, is likely to miss its target completely due to drift.

Other than crop dusting, mosquito spraying and fire fighting, all done at low levels, I don’t think I’ve ever seen anything applied by air. ( pause while people chime in with 100 things)

I was thinking maybe Agent Orange, but even tho they weren’t real particular about where that was sprayed, it was sprayed at a pretty low level too.

I read this thread yesterday, and I still had a moment just now, scrolling down the newest posts, thinking it was about paying employees in Denver.

Typo in thread title corrected.