Contrails signs of cold weather not nefarious actions

• Florida has banned “geoengineering,” or weather modification, in response to conspiracy theories about “chemtrails.”
• Scientists explain that the white streaks behind jets, called contrails, are ice crystals formed from engine exhaust in cold, humid air.
• The new law was passed despite no active weather modification programs being reported in Florida.

Conspiracists view vivid vapor trails crisscrossing the skies as proof our government is pumping chemicals into the atmosphere for sinister schemes, including but not limited to spawning or steering hurricanes.

But more than anything, winter has conspired against us. Lows in the 20s Sunday and the 30s through Wednesday — and much colder at cruising altitudes — are ideal for forming jet contrails that make some suspicious.

Relax. After weather-modification rumors swirled around a few ferocious hurricanes in 2024, Florida lawmakers last year banned so-called “geoengineering,” via Senate Bill 56. There’s no reported violations of the new law, which would mean up to a $100,000 fine and up to five years in jail.

And atmospheric scientists say the law is a solution seeking a problem: No one has tried such experiments in Florida for decades. But past cloud seeding for farming and for warfare sowed seeds of paranoia and distrust, they say, dating back to Vietnam-era American attempts at weaponizing weather. Nobody was very good at it, so most gave up.

“You would be hard-pressed to find operations in Florida that are impacted by this legislation,” Michael Splitt, assistant professor of meteorology at Florida Institute of Technology, said via email. The last cloud seeding in Florida may have been in 1957 by citrus growers, Splitt added.

There are, however, airports across the country that use “fog dispersal systems,” Splitt noted. They use dry ice to make fake fog — the kind you’d see at a rock concert — to help clear away real fog. Those “would appear to be banned from occurring or being tested in Florida,” Splitt added.

‘Chemtrails’ — a lot of hot air, left out in the cold

“Chemtrail” is a buzzword that refers to types of contrails, more a term among conspiracy circles than scientific ones.

A contrail (short for condensation trail) happens when hot, humid air from jet engines condenses into ice crystals, according to the National Weather Service. The trails often fade fast, especially in dry weather. But how they look and how long they last changes depending on the altitude, temperature, humidity, sunlight and wind speed a plane flies through.

In saturated high-humidity environments, contrails can linger for hours and spread among high-altitude, thin clouds or last long enough for multiple airplane trails to create a crisscross effect.

The main components of contrails are just water vapor frozen into ice crystals, mixed with some soot particles, sulfur compounds, carbon dioxide and other impurities from burnt jet fuel.

“Cooler temperatures (about -40 Celsius and less) and more moisture (close to ‘ice-saturation”’) are the ambient conditions needed for contrails, particularly long-lasting contrails” at the high altitudes jets travel, Splitt said, referring to research by Patrick Minnis of NASA’s Langley Research Center published in 2003.

“Mean hourly contrail frequencies reflect the pattern of commercial air traffic, with a rapid increase from sunrise to midmorning followed by a very gradual decrease during the remaining daylight hours,” Minnis’ paper says. “Although highly correlated with air traffic fuel use, contrail occurrence is governed by meteorological conditions.”

Tests and weird clouds seed conspiracy theories

But in recent years, rocket engine tests, geoengineering projects, widespread sickness, or just funky looking clouds have fueled allegations of chemtrails and X-files-like governmental conspiracies, despite countless reports to the contrary.

In recent months, a handful of residents in east Central Florida have reported contrails to the Florida Department of Environmental Protection’s public pollution notice website, including one on April 22 in Satellite Beach of “chemtrails sprayed over Satellite Beach” and one in Debary in Volusia County on Oct. 27.

DEP officials said Thursday they thoroughly review reports of suspected weather modification or geoengineering and have referred numerous reports to the Florida Department of Health for further review. But DEP has yet to receive “any reports or evidence suggesting that any individual or entity is in possession of, or operating, equipment prohibited under (the new state law).”

Can we steer a hurricane? Scientists say ‘no,’ military tried for 20 years

Florida bans geoengineering that doesn’t exist

Florida’s own agencies found no active geoengineering or weather‑modification programs operating before the state ban.

But Gov. Ron DeSantis signed the controversial bill banning “geoengineering and weather modification activities,” anyway, which many critics of the bill suspected was just to curb future efforts to fight climate change.

Sen. Ileana Garcia, R-Miami, sponsored the bill, saying the purpose was “… to separate fact from fiction” and to look into the theories in response to numerous requests from constituents and potentially disprove them.

Lawmaker in more than 30 states have introduced similar laws to stop geoengineering.

What did the bill do?

SB 56 repealed regulations allowing cloud seeding and requires DEP to create an email and online form for any residents with concerns about weather modification or to report sightings.

As of Oct. 1, publicly owned airports also have to submit monthly reports listed any aircraft equipped to disperse substances with atmospheric altering capabilities or lose state funding.

After hurricanes Helene and Milton in 2024, mass speculation about weather modification became so widespread that both NOAA and FEMA made fact-checking webpages.

“No one creates or steers hurricanes; the technology does not exist,” NOAA said in an October 2024 press release.

Project STORMFURY

But the military tried for decades to seed clouds to tame a hurricanes. Between 1962 and 1983, project STORMFURY involved military planes spreading silver iodide crystals into hurricanes. Scientists had discovered in 1946 that water vapor condenses on the microscopic particles to form ice crystals that drop down as rain.

Navy planes seeded four hurricanes. But researchers couldn’t tell whether the storms weakened because of the seeding or natural processes.

Even Microsoft founder Bill Gates — a favorite boogieman of conspiracists — has weighed in on hurricane suppression. More than decade ago, he proposed using hundreds of huge ocean-going tubs to drain warm water from the surface to deeper water, through a long tube, weakening storms as they form.

But like most air pollution, contrails from jet emissions are just a byproduct, not a conspiracy, Splitt said.

“The fact of the matter is that chemicals are getting into the air that can inadvertently alter the weather by influencing cloud microphysics such as from car and aircraft exhaust,” Splitt said. “These aren’t done with the express purpose of doing so.”

C. A. Bridges, a trending writer for the USA TODAY Network, contributed to this report.

Contact Waymer at (321) 261-5903 or jwaymer@floridatoday.com. Follow him on X at @JWayEnviro.