Organic aerosols and cloud droplets in the atmosphere

Image courtesy of PxHere

Karisa Steffens

For those of you that attended the presentation given by Isreal Silber on Jan. 28 that discussed some unusual phenomenon occurring in clouds in the arctic, you might be interested in hearing about the upcoming physics colloquium on campus. Sarah Petters from the University of North Carolina will be at Michigan Tech on Tuesday, Feb. 4 to give a presentation on organic aerosols and their effects on cloud droplets in the atmosphere. Her presentation will start at 11:00 a.m. and last until 12:00 p.m. on Tuesday, and will be taking place in room 138 of Fisher Hall.

Within the atmosphere, there is quite a bit of variety of compounds and atomic particles. One of these suspended submicron particles is known as aerosol. Many have heard of aerosols and are aware that they have a fairly large impact on a variety of events. Aerosols are known to contribute to the global burden of disease, regional haze, the carbon cycle and the global climate system.

Aerosols also have other effects as well. While likely not as well known, aerosols can regulate the distribution of water vapor as it condenses to form clouds. In this process, the aerosol particle acts as a cloud condensation nucleus, or the particle on which water condenses to form the cloud.

There is still much that is unknown about the effects on the climate as a result of this influence of aerosols. When we do think of the climate, after all, not many consider clouds as a heavy influence on what will occur. However, they do have more influence than people realize. Clouds affect how much sunlight reaches the surface of the Earth, and as a result, they can influence the temperatures we feel. Aerosols acting as cloud condensation nuclei can have more of an effect on climate change than people realize, as a result.

In this presentation, Petters will discuss molecular controls on cloud condensation nuclei efficiency of organic aerosols. By better understanding this process, Petters is hoping to be able to better predict aerosol-cloud interactions. By using a type of model that simulates the chemistry of the atmosphere (known as a chemical transport model), Petters believes that these effects can be modeled and predicted in the future.

Petters will continue to discuss what is currently understood about these interactions as well. After all, the process does not simply stop after the formation of a cloud droplet when aerosols begin to act as cloud condensation nuclei. The organic material may continue to react, evolving other physical properties of the cloud such as the ability to absorb moisture from the air (hygroscopicity), light absorption, and volatility.

Another aspect of this lecture will focus on the reactions that occur during physical processes and how they influence the final results of this interaction between aerosols and cloud droplets. Processes such as water evaporation are always occurring, and can influence the process of cloud creation even with aerosols involved.

This presentation will focus on events such as these physical interactions as a common theme. Many of the experiments focused on looking at how there may be a strong link between physical processes and the chemical changes occurring in aerosols. Looking at these studies from the mindset of a variety of different fields has given us insight into the sensitivity and impacts of these processes. This research has brought up new questions, and will continue to have people investigating the effects of aerosols on the climate, cloud formations, and public health.

The speaker Sarah Petters is a postdoctoral research associate studying aerosol processes at the University of North Carolina at Chapel Hill. We are happy to invite her here to give us more information on her research. This event is open to anyone who is interested in attending. For those of you who want to learn more, we do hope to see you there on Tuesday!