Deadly and destructive wildfires are raging through the Los Angeles area, and strong winds are literally fanning the flames.
As of Wednesday afternoon, four raging flames have killed two people, injured many more and destroyed more than 1,000 buildings, while threatening 28,000 others and forcing at least 70,000 people to evacuate.
Here’s how winds make wildfires more dangerous and harder to fight.
What types of spirits are these and why are they so powerful?
Santa Ana winds are strong winds that blow from dry areas inland to the coast, usually in the cooler months, for a few days to a week.
The National Weather Service says Santa Ana’s winds were as high as 129 km/h in some areas near LA early Wednesday, and could gust as high as 160 km/h in the hills and mountains.
Wind gusts of up to 95 km/h are expected through Thursday, the LA County Fire Department said Wednesday.
Those winds originate in the dry desert regions of Nevada, Utah, Idaho and southeastern Oregon, and become drier as they sweep over the mountains.
Peter Mullinax, a meteorologist with the weather service’s office in College Park, Md., called what the region is experiencing “extremely critical fire weather conditions,” due to the combination of strong high-altitude winds and very low humidity.
The Mountain Fire, which started earlier this week in California’s Ventura County, has grown to more than 80 square kilometers in size and called for the evacuation of about 10,000 people.
How does wind affect the spread of wildfires?
The faster the winds, the faster the fire spreads. Rule of thumb used by wildland firefighters that fires spread at 10 percent wind speed. For example, a wind speed of 25 km/h would allow a fire to spread at 2.5 km/h.
There are several reasons for this.
- Air helps provide fire and air and oxygen.
- It also thins and bends the flame towards the dead wood and other frontal oils. That can preheat and ignite sparks and embers in those new, dry sources of fuel, causing existing fires.
- The direction of the wind is the most important factor in the direction of the fire, said the National Weather Service.
- The wind also dries the plants, turning them into burning fuel.
Lindon Pronto, senior fire management expert for the European Fire Institute, said the ability of the Santa Ana winds to dry plants at their lowest humidity of the year is one of the “really dangerous effects.”
“The fuel itself is very much available in the fire and it can catch and contain the fire very quickly,” he told Reuters.
That includes increased fire risk and worse fire conditions already caused by climate change.
Sylvia Dee, an assistant professor and climate scientist at Rice University in Houston, said climate change has created hotter and drier conditions in the region, “and that creates a kind of box.”
How does it affect firefighting efforts?
As of midday Wednesday, 1,400 firefighters were on the ground, but aerial efforts were hampered by too much wind to fly firefighting planes, the Associated Press reported.
Winds can create turbulence, especially in mountainous terrain, or damage aircraft if they are too strong.
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