Timothy Tangherlini, a professor at UC Berkeley who has studied conspiracy theories, said it's common for them to be tied to other debunked theories in order for them to spread.

"They link them together in these super-conspiracy theories that are totalizing, and they give you an understanding of the world, a real us-versus-them thing," he said. "That's how conspiracy theories are held together."

Older conspiracy theories often help new conspiracies take root, offering people who are being exposed to the information some familiarity.

"Now next time you see it again, you see it from a couple of different sources, you think there may be something to that," Tangherlini said.

Conspiracy theories and misinformation have been particularly prevalent in the last couple of years, fueled by political polarization and distrust of government, official, scientific and journalistic sources, he said.

"Conspiracy theories are not really robust and you can make them fall apart, but they're incredibly resilient," he said. "That's why you see them come back to life."

In this case, he said, the storms that dumped more than a foot of rain in some parts of Southern California were more likely the result of climate change. For some of those who don't believe in climate change, or are politically opposed to action to address it, a conspiracy theory trying to lay blame on the storm to an unlikely, unseen, unproven force may seem more palatable than coming to terms to the visible effects of it.

"In some ways it's a counterargument," Tangherlini said. "People are saying this is due to climate change, and they're like, 'No, no, no, because in my ideological background I'm not a fan of climate change.'"

Mosher, who has watched some of the conspiracy videos, said he tries to see the misinformation as an opportunity, especially if it steers some people to the agency's website to learn more about the program.

"We're a public agency and we look for comments from the public, questions from the public, so we can respond to them," he said. "If people see those posts and contact us through email for our weather modification program and they have questions, we'll respond."

The agency, after all, is trying to be transparent about the program, he said.

"Our goal isn't to change people's minds — their opinions are their opinions," he said. "We just want to give them the information to help."

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