African Agricultural Fires will help NASA to Study Smoke-Cloud Interaction

African Agricultural Fires will help NASA to Study Smoke-Cloud Interaction

Credit: US Embassy in Namibia

Scientists found some unexpected new features during an analysis of the African Smoke-Cloud connection.

Smoke is an airborne mixture of solid and liquid particles and gases, which is emitted when the combustion of a material takes place. It also carries the quantity of air that is mixed into the mass. The chemical composition of smoke is determined by the nature of the burning material and the conditions of combustion. If a sufficient amount of Oxygen is available, small quantities of smoke are produced as the burning takes place at a high temperature. In this case, both Carbon and Hydrogen are completely oxidized to Water and Carbon Dioxide. Similarly, Nitrogen and Sulfur are converted to Nitrogen Oxides and Sulfur Dioxide.

On the other hand, incomplete combustion can lead to a number of toxic compounds. For instance, you may get Hydrogen instead of water and Carbon Monoxide in place of Carbon Dioxide. Likewise, Nitrogen can lead to Ammonia and Hydrogen Cyanide while the burning of Sulfur can result in Hydrogen Sulfide. Additionally, a lot of Hydrocarbons are also produced in such a fire.

Despite all its useful applications like pest control and communication, it is an unwanted byproduct of all fires. Consequently, it is the largest contributor to air pollution and affects the environment in a number of different ways. The most common among them is the burning of fossil fuels for power purposes. A lot of poor countries rely on the combustion of biomass to fulfill their energy needs. Hence, a significant amount of smoke is added to their environment on a regular basis. The ever-increasing number of motor vehicles is equally responsible for the increment in air pollution as it is a major source of the harmful smoke. Similarly, controlled agricultural fires pollute the nearby air with substantial quantities of smoke.

It is a well-known fact that warm air rises upwards so all the plumes of smoke travel into the vicinity of clouds. This offers an amazing opportunity to the scientists to analyze the interactions between the tiny smoke particles and cloud droplets. Recently, the researchers at NASA decided to have another look at the natural laboratory above a 2000-mile-long plume of smoke from the African agricultural fires. P-3 research aircraft of NASA carried a team of scientists to this region (for the 3rd time) as part of the Observations of Aerosols Above Clouds and their Interactions mission (ORACLES). Paquita Zuidema, a Co-principal Investigator of the ORACLES deployment who is an Atmospheric Scientist at the University of Miami, described that by saying,

The cloud deck in the southeast Atlantic is one of the largest on the globe. At the same time, the smoke layer stretches all the way to South America. The combination of smoke and clouds generates enough atmospheric warming to affect precipitation patterns over Africa in climate models, making it imperative to develop better confidence in the model predictions.”

All the aerosols that are small enough to travel on prevailing winds are considered an extremely important of our atmosphere. On the basis of their absorption capabilities, aerosols can be divided into two categories. The first one of them is Light-colored Aerosols which reflect sunlight to cause a cooling effect. On the other hand, Dark-colored Aerosols absorb the heat from the sun to cause a warming effect.

Smoke has the potential to act as both and its behavior is dependent on its constituent particles. It is the basic purpose of the ORACLES mission to find how clouds and aerosols cooperate to determine a balanced climate. Additionally, it will provide insights about the microphysical effects smoke particles has on cloud droplets. Rob Wood, an Atmospheric Scientist at the University of Washington who is also a Co-principal Investigator of the mission, elaborated that in the following words:

We have major questions about how aerosol particles impact clouds and climate, and these interactions differ depending upon where you are on Earth. Last year in August, we saw a lot of physical contact between the smoke and the clouds. Cloud droplets actually formed on these smoke particles and there was a big increase in the number of droplets compared to what it would be like without the smoke.”

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