Scientists have identified the weather conditions that created the so-called “dry lightning” phenomenon that started some of California’s most devastating wildfires.
These conditions can be modeled over the long term to improve the prediction of these very rare weather events.
This will help governments and emergency services respond more quickly as extreme wildfires increase in frequency and size.
Dry lightning occurs when there is less than 2.5 mm of rain.
The troposphere, the lower part of Earth’s atmosphere, is so dry that rain that normally comes with lightning evaporates before it falls.
Now, scientists have identified the conditions that allow this:
- higher world temperatures
- dryness in the lower troposphere
- humidity and instability in the middle part of the troposphere
High temperatures and dryness are also ideal conditions for burning vegetation.
And it is believed that in the coming years, global warming will increase temperatures and reduce precipitation in California.
As of August 2020, more than 12,000 lightning strikes started more than 650 wildfires in California, burned more than 600,000 hectares of land, hundreds of thousands of people were evacuated, the equivalent of approximately 840,000 football fields.
Lightning is also believed to have exacerbated the McKinney fire, which last week was the state’s biggest fire this year.
The paper’s lead author, Dmitri Kalashnikov of Washington State University, said multiple fire ignitions in dry lightning events make them harder to control.
“Compare that with a fire caused by humans,” he said. “This is a location that is usually close to people’s reach, whether criminal or incidental. So response to extinguishing the fire can be much faster.”
However, dry lightning fires can start more than 100 km from the nearest road and spread quickly before firefighters can reach the scene.
According to the study, lightning started 28.5% of wildfires in California between 1987 and 2020, but caused 50% of the land to burn.
Image: DAVID MCNEW/GETTY IMAGES
Deepti Singh, co-author of the study, said the paper could help “understand dry lightning meteorology in this region.” [que] It is crucial in informing the forecast, helping to better limit the risk of future wildfire ignitions in California.”
Scientists now hope to study dry lightning in other parts of the western US, including Oregon and the Rocky Mountains.
– This text was originally published at https://www.bbc.com/portuguese/internacional-62517190.
source: Noticias
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