Many parts of the United States, especially the West, are once again in the crosshairs of devastating wildfires this year. Amid a summer of scorching temperatures and dry winds, firefighters spent weeks trying to contain one escalating fire after another.
In press conferences and alerts to residents, firefighters can agree on numbers on how many thousands of acres have burned and talk about how “red flag conditions” are fueling “extreme fire behavior” that hinders their efforts to increase the rate of a “complex fire.” fire” that is “enclosed”.
Here’s a guide to help you understand some of the terms officials use when discussing wildfires:
When fire officials report that a fire is, say, 30 percent under control, it means that 30 percent of the boundary of the fire is enclosed by barriers such as rivers, streams, highways, or areas that have already scorched, leaving no vegetation. is to ignite. Other times, these containment lines are 10- to 12-foot-wide trenches that crews dug along the edge of the fire — sometimes using bulldozers — to keep the fire from spreading.
When officials say a fire has been contained 100 percent, it doesn’t mean it’s extinguished. It just means that firefighters have it completely surrounded by a perimeter; it can burn for weeks or months. Once a fire has been declared ‘controlled’, it is over.
Red Flag Warning
A red flag warning is the highest warning issued by the National Weather Service for conditions that could lead to extreme fire behavior within 24 hours. Forecasters will announce such a warning when warm temperatures (over 75 degrees), very low humidity (less than 25 percent) and stronger winds (at least 25 mph) join forces to create an increased risk of fire hazard.
If you live in an area subject to a red flag warning, make sure you:
Remove dead weeds and vegetation from around your home.
Empty your roof and gutters of dry leaves and other debris.
Remove flammable household items outside, such as brooms and cushions on patio furniture.
Do not use lawnmowers on dry land.
Extreme fire behaviour
In general, extreme fire behavior includes some or all of the following:
A high spread
Flames grow through the branches and leaves of trees and shrubs, unaided by the flames on the ground
The existence of fire vortices, which are vortices of hot air and gases that rise from a ground fire and carry debris, flames and smoke into the sky. They range from less than a foot to over 500 feet in diameter. The largest resemble the intensity of a small tornado.
The presence of a convection column, which directs gases, smoke, fly ash, particulates and other waste produced by a fire directly into the air and spreads vertically rather than horizontally
When two or more wildfires burn close together in the same area, they are often referred to as a “complex” and are attacked by firefighters under a unified command.
In the summer of 2020, a siege from dry lightning caused about 40 fires in three national forests in northwestern California. They all merged into the August Complex fire. It burned over a million acres in total, leading to a new term: “gigafire.”
When you hear of a 100,000-acre fire, that’s a description of the total area burned, not what’s actively burning at the time.
But, as Ernesto Alvarado, a professor of wildfire science at the University of Washington, explained, “There’s no way you can map 100,000 acres with people on the ground.”
Authorities are instead turning to planes, which use infrared cameras, and weather satellites, which can take an image of a fire zone every five minutes. Firefighters can create real-time maps from these data files, which can then be supplemented with ground information to map any major fire.