How do clouds influence Earth’s climate?

A recent grant from the Department of Energy’s Office of Science will fund a three-year project led by the University of Houston to investigate the impact of clouds on our planet’s climate. By studying the interaction between clouds and the tiny particles that comprise them –  known as aerosols – the scientists will try to better understand how cloud formation and location in the atmosphere maintain the Earth’s temperature.

“Clouds cover about 70 percent of the Earth’s surface,” said project leader Professor Yunsoo Choi. “They are one of the most essential components of the global climate system because of their regulation of surface precipitation and the atmosphere’s radiation balance,” i.e. the difference between the amount of solar radiation absorbed by the Earth and the amount released back into space.

The scientists will focus on how aerosols form various types of clouds with different radiative impacts. Aerosols – which can be both inorganic, consisting of sulfates, nitrates, or ammonium, and organic, such as black carbon or soil particles – play a fundamental role in cloud formation. When water vapor condenses on their surface, it forms cloud condensing nuclei, which are essentially the “seeds” from which clouds grow.

“The formation of cloud droplets typically cannot occur without aerosols. Clouds strongly affect the Earth’s energy balance by trapping heat near the surface and reflecting solar radiation back to space,” explained study co-author Ali Mousavinezhad.

To better understand the role of aerosols in cloud formation and their impact on the Earth’s climate, the researchers will use data from the Department of Energy-funded Atmospheric Radiation Measurement’s TRacking Aerosol Convection Interaction ExpeRiment, together with data from an aerosol-cloud interaction targeted modelling system.

“For me, the most interesting aspect of this project is the combination of a modeling system with the dataset from an ongoing campaign, happening right here in our backyard,” said study co-author Arman Pouyaei. “The idea is to use this dataset in a novel technical approach. We hope to learn important lessons about the capabilities of current modeling frameworks in representing the impacts of aerosols on cloud formation and climate change.”  

“Climate change is primarily discussed in terms of greenhouse gases. By the end of this project, we will gain a deeper understanding of how aerosols as air pollutants influence cloud formation and our planet’s climate, which I am very excited about,” concluded Mousavinezhad.

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By Andrei Ionescu, Earth.com Staff Writer