Smoke produced by large wildfires can be equal to a volcano

Above: Satellite photo taken August 2, 2017 showing smoke from some of the wildfires in British Columbia. The red dots represent heat detected by a sensor on the satellite.

It is not easy to measure and quantify the composition of the smoke and the amount of particulate matter that a huge wildfire produces when intense, large-scale burning forms towering pyrocumulus clouds that climb tens of thousands of feet into the sky. This launches the byproducts of combustion into the  stratosphere — the second layer of Earth’s atmosphere, above the troposphere. Once introduced at that level they have been tracked while circling the planet multiple times.

Below is an excerpt from an article by Megan Gannon at Live Science, which points out similarities between large wildfire events and volcanos.

For comparison, the explosive 2008 eruption of Mount Kasatochi, an island volcano in Alaska, sent about 0.7 to 0.9 teragrams (nearly 1 million tons) of aerosols — tiny, suspended particles — into the stratosphere, Peterson said. For months afterward, people around the Northern Hemisphere documented unusually colored sunsets, thanks to the sulfate aerosols and ash the volcano injected into the atmosphere.

Peterson’s team estimated that the British Columbia pyroCb event sent about 0.1 to 0.3 teragrams (about 200,000 tons) of aerosols into the stratosphere — which is comparable to the amount seen with a moderate volcanic event, and more than the total stratospheric impact of the entire 2013 fire season in North America, he said.

It’s well known that catastrophic volcanoes can influence the global climate. The huge 1991 eruption of Mount Pinatubo in the Philippines, one of the largest in living memory, lowered temperatures around the world by an average of 0.9 degrees Fahrenheit (0.5 degrees Celsius).

As an example of the wildfire activity in British Columbia last year, here is an excerpt from an article posted August 9 at Wildfire Today:

The wildfire situation in British Columbia has not gotten any better in the last several days. Currently there are 128 active wildfires in the province, with four of them being larger than 50,000 hectares (123,000 acres). The largest, the Hanceville Riske Creek Fire, is getting closer to half a million acres each day.

Since April 1, approximately 591,280 hectares (1,461,082 acres) have burned in 900 fires in BC.

  • Hanceville Riske Creek, 172,000 hectares (425,000 acres) approximately 60 km southwest of Williams Lake.
  • Elephant Hill, 117,000 hectares (289,000 acres), near Ashcroft.
  • Tautri Lake, 76,000 hectares (188,000 acres), 80 km northwest of Williams Lake.
  • Baezaeko River-Quesnel West, 53,000 hectares (131,000 acres).

More than 400 additional firefighters from Australia, New Zealand, Mexico and the US are expected to arrive in BC this week. Other firefighters from Australia have been in the province for a couple of weeks. More than 100 firefighters arrived from Mexico since Saturday of last week…

 

Pyrocumulonimbus clouds

Above: Bureau of Meteorology, Australia

(Originally published at 11:38 a.m. MST January 11, 2017)

The Australian Government’s Bureau of Meteorology has an excellent article about clouds that can form over rapidly burning vegetation fires. Pyrocumulus clouds can develop into pyrocumulonimbus that can generate lightning miles away from the fire.  Below are excerpts from the article.


What are pyrocumulonimbus clouds?

They’re a thunderstorm that forms in the smoke plume of a fire (or nuclear bomb blast, or volcanic ash cloud). In Australia they most commonly form in large and intense bushfire smoke plumes. (The official name for clouds that form this way is ‘flammagenitus‘, but they’re commonly known as pyrocumulonimbus.)

How do they form?

The intense heat from the fire causes air to rise rapidly in the smoke plume. The rising hot air is turbulent and draws in cooler air from outside the plume, which helps cool the plume as it rises. As the plume rises to higher and higher elevations the atmospheric pressure reduces, causing the plume air to expand and cool even further. If it cools enough, the moisture in the plume air will condense and forms cumulus cloud, which, because it comes from the fire plume, we call ‘pyrocumulus’. The condensation process causes latent heat to be released, which makes the cloud warmer and more buoyant and causes the cloud air to accelerate upwards. Further expansion and cooling causes more moisture to condense and the cloud air to accelerate upwards even more. In the right conditions the cloud can accelerate into the lower stratosphere before losing buoyancy. Collisions of ice particles in the very cold upper parts of these clouds cause a build-up of electrical charge, which is released by giant sparks—lightning. Having produced a thunderstorm, the cloud is now known as ‘pyrocumulonimbus’.

Thunderstorm initiated by a wildfire

This time-lapse video of the pyrocumulus cloud over the Sedgerly Fire in Queensland, Australia is fascinating. According to the description by the Bushfire Convective Plume Experiment it shows a thunderstorm initiated by the fire. If you look closely you will see rain and lightning.

Impressive convection column on Pioneer Fire is being studied by researchers

Above: The photo above was taken from the research aircraft August 30 by Nick Guy of the University of Wyoming’s Atmospheric Science department.

The Fire Weather Research Laboratory from San Jose State University is conducting research from an aircraft flying over the Pioneer Fire in central Idaho. Today using N2UW, a twin engine 1977 Beech 200T King Air, they flew for over three hours at 27,000 feet studying the fire for the RaDFire project.

The aircraft is outfitted with a ton of instruments including Doppler radar. Craig Clements, Associate Professor in the Meteorology Dept. at SJSU, described it for us:

The radar is called the Wyoming Cloud Radar (WCR). It’s on the aircraft, points up, down, and down-forward to get horizontal winds and vertical winds. The goal of the RadFIRE (Rapid Deployments to Wildfires Campaign) is to get data on plume dynamics from ground based mobile Doppler Lidar. But we were awarded 10 flight hours to test the WCR to see if it works in smoke plumes. And it does so well, more than we can imagine!

The group has been known to fly through the convection column. I’ve done that a few times and it’s an interesting experience — it can get a little turbulent, as you might expect.

On Monday they said the top of the pyrocumulus cloud over the fire topped out above 30,000 feet. In Tuesday’s photos it was at about 25,000 feet but toward the end of the day the top got up to at least 32,000 feet, Mr. Clements said.

The project is sponsored by the National Science Foundation and it’s being led by San Jose State University. Other collaborators on the project are David Kingsmill at the University of Colorado Boulder, and the University of Wyoming King Air team.

Since it started on July 18 the Pioneer Fire has burned over 140,000 acres.

This last photo of the convection column was not taken by the researchers. It was shot by Steve Botti in Stanley on August 29, more than 20 miles away from the fire.

Pioneer Fire
Pioneer Fire, as seen from Stanley August 29, 2016. Via Mike Warren.

Where does the moisture in a pyrocumulus cloud come from?

Above: CNN Meteorologist Chad Myers explains pyrocumulus clouds. This is a screenshot from Mr. Myers’ 52-second video. The Weather Channel has a similar explanatory video.

Cumulus clouds are puffy clouds, usually having a somewhat flat base but with some vertical development that gives them rounded towers on top. They can form when the sun heats the earth, which then heats the air above it causing the warmer air to rise. Rising air cools and the relative humidity increases. If it reaches 100 percent, water vapor condenses forming a visible cloud.

Above: time-lapse video of pyrocumulus over the King Fire in California.

Clouds can also form over vegetation fires. In some cases a very intense fire can produce enough heat that the air rises very quickly. If it is not dispersed laterally by wind it can rise high enough that a cloud forms. This can look like a cumulus cloud, but when they form over a fire they are called pyrocumulus clouds.

Occasionally these clouds will produce rain or even lightning. Water requires a non-gaseous surface to make the transition from a vapor to a liquid. Smoke helps out by contributing very small particles that are used as condensation nuclei on which water droplets form, to create clouds or rain.

If pyrocumulus clouds grow large they resemble cumulonimbus, thunderstorm clouds. What goes up must come down, and if not disturbed by a strong wind during the dissipating stage the updrafts can reverse and become downdrafts. This is sometimes called a “collapsing column”. When that descending air hits the ground it spreads out, sometimes in all directions, and can quickly and drastically change the wind direction at a given point on a fire. This can be fatal if firefighters find themselves in the wrong location at the wrong time.

I had always assumed that much of the moisture that formed a pyrocumulus came from a byproduct of combustion — water vapor — something that many burning fuels create. (Some TV meteorologists also make the assumption about the sources of the moisture.) A great deal of water vapor is produced when vegetation burns, and the higher the fuel moisture the more water vapor is created.

But I wanted to confirm that assumption before I wrote this article, and it turns out I was wrong. I found two research papers that were devoted to the subject and they were mostly in agreement. As the byproducts of combustion rise above a fire the water vapor is rapidly diluted before it reaches the condensation level, or what becomes the base of the pyrocumulus. One group of researchers in Germany calculated that 10% of the moisture in a pyrocumulus comes from the fire.

Others with the Bushfire & Natural Hazards CRC in Melbourne, Victoria, Australia determined that the contribution of water vapor from the fire is negligible since it is diluted before it reaches the height of the cloud:

Fire plumes entrain large amounts of environmental air as they ascend, which greatly dilutes the plume gases, including the fire moisture. Figure 3 shows the fire moisture dilution for the moist fire simulation(right panels of Fig. 2). The lightening shades of blue with height demonstrate the fire moisture dilution. When the plume reaches the condensation level (4.5 km) there is barely any fire moisture evident to contribute to cloud development. The dilution rate may be sensitive to fire size and intensity.

pyrocumulus moisture
From research by the Bushfire & Natural Hazards CRC, Melbourne, Victoria.

Continue reading “Where does the moisture in a pyrocumulus cloud come from?”

Wildfire briefing, August 23, 2013

Firefighter dies in Portugal

A female firefighter was killed and nine were injured Thursday on a wildfire in Portugal near the small city of Tondela. Commander Antonio Ribeiro of the Serra de Caramulo firefighters said the crew ran from the fire but the firefighter who died fled in the wrong direction. Euronews reports that three firefighters have died this month. High temperatures and strong winds have contributed to the spread of 13 large fires in Portugal.

The national wildfire situation

Today there are 49 uncontained large fires listed on the national Situation Report in the United States, and that number does not include individual fires within complexes. There are currently 854,480 acres within the perimeters of those active fires. The national Preparedness Level has reached the highest category, PL 5, for the first time since 2008. And while it may seem like much of the west is on fire, the number of acres burned to date, 3.4 million, is much less than average, which is 5.6 million.

Competition for firefighting resources is occurring. There is only one California-based Type 1 or Type 2 incident management team available that is not assigned to a fire; 33 IMTeams are assigned nationwide. But surprisingly, there are no Area Command Teams committed.

We have 11 large and very large air tankers working right now on exclusive use contracts, and there are another 9 that the USFS has borrowed from the military, the state of Alaska, and the Canadian government. In 2002 there were 44 large air tankers on contract.

Forest Service runs out of money for firefighting

For the sixth time in the last ten years the U.S. Forest Service has run out of funds for suppressing wildfires. Even though the number of acres burned to date this year is below average, the USFS is having to divert funds from other non-fire accounts in order to cover the shortfall. This is due in part to reductions in the amount of money Congress allocates for the FLAME fund, which is supposed to fund firefighting while protecting other accounts. The Washington Post has more details.

Scott Olsen writes about a firefighter’s first day on the job

You may have seen the articles written last year by W. Scott Olsen, a professor of English at Concordia College in Moorhead, Minnesota about “the war on wildfires out west, meeting shot-callers and looking at the operation from the inside”. He has just published a new article at the Huffington Post about a wildland firefighter’s first day on the job.

Granite Mountain 19

The issues surrounding the deaths of the 19 members of the Granite Mountain Hotshots June 30 on the Yarnell Hill Fire continue to make the news. Firefighters with the New York City Fire Department have raised $30,000 so far for the families of the 19, and they are hoping to add to that total. The Prescott Daily Courier asked the candidates for Mayor and the City Council to express their positions on the discrepancy between the benefits for the seasonal and full time members of the crew. And there is a debate about whether the city’s hotshot crew should be rebuilt.

Investigative reporter John Dougherty has two recent articles about the Yarnell Hill Fire: “Yarnell Hill Fire: The Granite Mountain Hotshots Never Should’ve Been Deployed, Mounting Evidence Shows” and “A Granite Mountain Hotshot’s Father Says the Blaze That Incinerated His Son Could’ve Been Controlled“.

Montana residents contribute for free coffee for firefighters

Residents near Lolo, Montana are contributing to a fund to provide free, good quality coffee for firefighters working on the Lolo Creek Complex. According to an article at KZBK, Samantha Harris, a barista at Florence Coffee Company in Lolo, said customers have been donating money to give firefighters coffee.

“We have a huge tab here so all the firefighters’ coffee is paid for,” Harris said. “Which has been really fun to tell them their coffee is free.” The tab is at nearly $300, she said.

Florence Coffee Company is at 11880 HWY 93 in South Lolo, Montana.

Photos of pyrocumulus

The Alaska Dispatch has some very impressive photos of pyrocumulus smoke columns caused by wildfires.

Goat manure fire stinks up town

A burning pile of goat manure is affecting the quality of life for residents of Windsor, Vermont. The pile ignited from spontaneous combustion Wednesday at George Redick’s 800-goat dairy. Windsor Town Manager Tom Marsh said he could smell the fire at his home which is five miles from the dairy.