It's called FAA FAR 101 (FAR101):
You should be aware of the risks and proper handling of something that would be dangerous for commercial aircraft or people below.
I know the whole "Big Sky" theory, but eventually if enough people do this, it's gonna get hit by a jet.
Ingestion of this at 30,000 ft will wreck an engine or wrap around control surfaces, potentially rendering them inoperable. Those would probably be recoverable, but if it sheared off pitot tubes in just the right way - it could be a disaster.
I hate to be a wet blanket but - although these images are stunning - it's not something we should be doing without serious consideration of the possible risks or taking the appropriate precautions.
NOAA has been doing this for years and launches ~75,000 per year. (According to another statistic I saw, 800 of them are released worldwide very day. That's nearly 300,000 per year.)
I'm glad you are aware of the Big Sky theory, as that is what I would have pointed you to.
If someone does intend to do this, a call to the FAA letting them know beforehand would not harm anyone. I didn't, but should have.
I wouldn't be so sure. In fact, I would rather assume that the FAA would want to stop the launch before they can rest assured it's safe.