According to Wikipedia, EIA may refer to:

* Edmonton International Airport
* Electronic Industries Alliance, a US trade organization
* Energy Information Administration, a part of the U.S. Department of Energy
* Environmental Impact Assessment, an assessment of the likely impact of a project
* Environmental Investigation Agency, a non-governmental organization
* Enzyme Immuno Assay, see ELISA
* Equine Infectious Anemia, a horse disease
* Equity-indexed annuity, a financial product
* Evergreen International Airlines, an American airline with ICAO code EIA
* Exercise-induced anaphylaxis, a medical condition
* Exercise-induced asthma, a medical condition
* External iliac artery, an artery
http://en.wikipedia.org/wiki/EIA

I don't think anybody would need a cloud large enough that a 747 is required to carry all the necessary chemicals, I think most seeding is done with much smaller planes (think crop duster) and/or rockets.

"(Evergreen International Airlines) is completing final modifications on a Boeing 747-200 aircraft modified to be a Supertanker to fight fires. The airline was awaiting final approval from the FAA, which arrived in the last week of October 2006. With this it will be adding a giant aircraft to its current fleet of fire fighting aircraft. This Supertanker will offer at least seven times more drop capability as compared to the current largest airtanker. Its capacity to carry a large volume of Fire retardant will considerably decrease the time taken in fighting large fires."

http://en.wikipedia.org/wiki/Evergreen_International_Airlines

I think that's what this is. It was so high up probably because it was a demo or test run.