He is a self-described measurer of all things very small.
Over the past 25 years, those very small things have predominantly been aerosols. In the atmosphere, they range from a few nanometers to a micrometer wide.
A bundle of 100 micrometers, laid side by side, equals the width of a single human hair. But in the realm of atmospheric particles, a micrometer is gargantuan.
Aerosols are tiny particles suspended in the air as either a liquid or solid. They play an important role in scattering and absorbing solar radiation and are needed to form clouds. In sum, tiny aerosols play a big role in determining Earth’s climate.