Sep 04 , 2019
The William flat fires have been all over the news lately. According to reports, the wildfire had born about 40,000 acres of land. The fire which was burning on the Colville Indian Reservation triggered a thunderstorm on Thursday 8th of August, 2019.
And this became the headline of most media houses in the United States as scientists were able to fly through its clouds. It’s one of the only times scientists were able to fly through such thunderstorm. Interestingly, they took pictures of the phenomenon from a jet and took its measurement.
The phenomenon is known as pyrocumulonimbus or PyroCb, and most people don’t know about it. In this article, we will teach you a lot of things about pyrocumulonimbus.
Pyrocumulonimbus is often referred to as the fire breathing dragon of clouds. It’s a thunderstorm that’s wildfire driven. It forms above a heat source and sometimes extinguishes the fire that triggered it.
PyroCb doesn’t just happen; it occurs once in a while when the wildfire is hot enough to generate updrafts. And when it manifests extremely, it could inject plenty of smoke and other biomass burning emissions into the lower stratosphere.
According to meteorologists, pryroCb occurs naturally. And they are hypothesized as part of theoretical “nuclear winter” scenarios through anthropogenesis.
How Do Pyrocumulonimbus Clouds Form?
Like I mentioned earlier, pyrocumulonimbus clouds are a thunderstorm that is created by the smoke plume of wildfire. In this section, you will learn how these cloud form and how possible you can predict them.
Ordinarily, when the heat intensity from wildfires is high, it makes the air to rise quickly in the smoke plume. Most times, this rising hot air isn’t stable, and it attracts cooler air outside which cools the plume as it rises.
As the plume rises to a higher altitude, the atmospheric pressure will reduce. This will make the plume air to expand and cool better. At this stage, if the plume air is cool enough, its moisture will condense to form a cumulous cloud. And this cloud is called pyrocumulus cloud because it’s a product of the wildfire plume.
Furthermore, the condensation process triggers the release of latent heat. Latent heat makes the cloud warmer and directs its air to accelerate upward. If air expands further and cools more, more moisture will condense, and the cloud air will move upward further. If the condition is right, the cloud could move into the lower stratosphere before it loses its buoyancy.
In the very cold upper part of the cloud, there will be a collision of ice particles which could lead to electrical charge build-up. Most times, the electrical charge released giant sparks lightning. At this stage, it would have produced a thunderstorm; the cloud is what we called pyrocumulonimbus.
Here is the pyrocumulonimbus forming process at a glance;
- The Pyrocumulonimbus cycle starts when a plume of smoke, hot, and turbulent air rises
- Turbulence attracts cooler air into the plume which makes it to expand and cool as it elevates
- When the plume rises to an extent, low atmospheric pressure will cause the plume air cool. At this stage, the cloud will form.
- If the atmosphere is unstable, a thunderstorm will develop, which is called a pyrocumulonimbus cloud.
- At this stage, rain in the cloud will evaporate and cool once it contacts dry air; this process will produce a downburst.
- Lightning may or may not be produced. If it produces, it could ignite a new fire.
Why Are Pyrocumulonimbus Cloud Dangerous?
Pyrocumulonimbus clouds are dangerous; they can trigger unpredictable and dangerous in wildfire behavior. Here are some of the reasons why Pyrocumulonimbus clouds are dangerous;
Change in Fire Direction and Intensity
Pyrocumulonimbus clouds make fire direction and intensity unpredictable. They could trigger severe updraft which can suck in enough air to develop strong winds usually drawn from all directions towards the plume. This will make the fire to burn and spread faster.
The possibility of igniting a spot fire is another reason the pyrocumulonimbus phenomenon is dangerous. Spore fires occurred when a fire ignited outside a burning unit due to windborne embers.
Whenever a pyrocumulonimbus cloud is created, lightning is likely to form such a cloud.
Most times, when pyrocumulonimbus cloud forms, it causes air pollution. And it’s advisable to always have an N95 respirator to keep you safe.