KERR COUNTY, Texas – Misinformation is circulating about the recent Hill Country floods, with some questioning if the weather was modified through a process called “cloud seeding.”
What is cloud seeding?
Cloud seeding is an attempt to squeeze a little more rain out of a cloud than it would naturally drop.
CLOUD SEEDING:
- Can’t bust a drought
- Can’t cause a flood
- Can’t make clouds out of thin air
- CAN sometimes slightly increase the amount of rain or snow
- Can sometimes increase precipitation by 10%-16%
- Needs clouds with specific characteristics (it’s picky!)
- Is hard to prove due to natural variability of weather (i.e., what would’ve happened without seeding?)
- Theoretically speaking: If a storm like July 4’s in Kerr County was seeded, it would maybe account for about 1.5″ of the 13″ of rain that fell.
Although cloud seeding periodically occurs in the Texas Hill Country, it’s physically impossible for cloud seeding to cause the recent flood.
Flooding storms will flood. Cloud seeding can’t cause floods because floods require broader atmospheric conditions than what cloud seeding can provide.
THE BASICS
The concept of cloud seeding goes back to the 1940s, but it wasn’t until 2017 when it was scientifically proven to slightly increase snowfall in a small part of Idaho.
Cloud seeding always starts with a cloud that can already make precipitation.
Most clouds are inefficient at making rain or snow and leave a lot of moisture left unused, so cloud seeding nudges the cloud to be more efficient and use a little more of the available moisture in the cloud.
Like meticulously folding your toothpaste in order to get the last little bit out of the tube - or - properly inflating your tires to improve gas mileage. It won’t change much, but it helps a little.
Cloud seeding wasn’t part of this storm
The Kerr County area experienced an extraordinary rainfall event, with 10 to 13 inches of rain falling in just a few hours on July 4.
In response to claims, Mike Flynn, former National Security Advisor and CEO of Rainmaker, a cloud-seeding company, said, “Rainmaker did not operate in the affected area on the 3rd or 4th or contribute to the floods that occurred over the region.”
On Monday, U.S. Senator Ted Cruz said to the best of his knowledge, there is “zero evidence” to support any claims related to weather modification.
“We cannot control the weather, and we can barely even influence it,” KSAT Meteorologist Adam Caskey said.
According to the U.S. Government Accountability Office, “cloud seeding is an 80-year-old technology that adds tiny particles—usually silver iodide crystals—to clouds to trigger rain or snow.” There is very little federal government involvement in the process.
Some states, including Texas, permit programs to research cloud seeding. The Texas Department of Licensing and Regulation tracks the location of these projects and issues permits and licenses to organizations. A map of these projects shows a cluster to the south of Kerr County.
How cloud seeding works
Water in a cloud needs something to freeze onto (nuclei) such as dust, aerosols, pollutants, minerals, etc. in order to form ice crystals. Cloud seeding uses silver iodide as an artificial nuclei in order to create more ice crystals in the cold (5°F to 23°) part of a cloud, which can then cause more rain or snow.
Silver iodide is used because it has the same hexagonal structure as ice and is non-toxic. Actually, silver is naturally occurring in our water and soil. Scientists have had a hard time finding an increase in silver where seeding has occurred.
Traditionally, an airplane flies in front of the wind that blows into a large cloud or through the top of the cloud while spraying non-toxic silver iodide. However, some ground-based delivery systems are used in the areas where terrain induced precipitation occurs over mountains.
Research is currently underway to utilize cloud seeding as a means of increasing mountain snowpack in parts of the drought-stricken Western U.S., particularly for communities that rely on a melting snowpack for their summer water supply.
However, it remains complicated to statistically quantify.
Other cloud seeding studies attempt to suppress hail formation and erode fog.
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