Fiery Clouds Powerful Enough to Inject Aerosols into Stratosphere

It is well known that volcanoes are powerful enough to inject sulfate aerosols into the stratosphere during an eruption. But, there are also other ways that these particles can reach this atmospheric layer. Pyro cumulonimbus storms thrive above a strong heat source such as a wildfire. When these fires get hot enough, they generate strong upward air currents that carry water vapor, ash, and smoke. The particles absorb the condensed water vapor and turn into cloud droplets. With enough water vapor, these clouds can turn into dangerous thunderstorms and either put out the fire with the rain or start a new one with the lightning.

Diagram of smoke from wildfire

These storms introduce smoke and ash from wildfires into the lower stratosphere via convection of the air currents produced by the intense heat from the fires. Jet stream winds can quickly transport the particles large distances and cause a global effect. It is important to know the composition of the smoke from the wildfires since that can either positively or negatively affect the climate. For example, sulfur aerosols in the stratosphere will have a cooling effect due to their high reflectivity of sunlight. On the other hand, the darker particles tend to absorb radiation and causes a heating effect.

An image of a jet flying by a pyrocumulonimbus cloud

Studies from the U.S Naval Research Laboratory on the 2017 wildfire in British Columbia, Canada shows that the event sent 200,000 tons of aerosols into the stratosphere. During the 2018 eruption of Mount Kasatochi, about 1 million tons of aerosols were injected into the stratosphere. Wildfires have been gaining more attention given that California had one of the deadliest wildfire seasons in 2018. Wildfires occur more often than volcanic eruptions and have a detrimental impact to the human health via air quality. For more information on this article click here.