Why atmospheric nanoparticles grow at similar rates everywhere
Aerosols have a profound influence on air quality, human health, clouds and climate, but new particle formation in the atmosphere has remained a scientific conundrum. Large fractions of airborne fine particulate matter consist of secondary organic aerosols (SOA) formed by gas-to-particle conversion of organic precursor molecules in the atmosphere. The growth rates of these atmospheric…
Atmospheric nanoparticles, or aerosols, have a significant impact on air quality, human health, clouds, and climate. However, the growth rates of these tiny particles have been a scientific mystery as they are often smaller and less dependent on vapor concentration than expected. Scientists at the Max Planck Institute for Chemistry in Mainz have now developed a kinetic multilayer model that explains the uniform growth rates observed in both field measurements and laboratory experiments.
Their research reveals that temperature-dependent changes in organic-vapor production, volatility, and diffusivity largely offset each other, buffering the rate of nanoparticle growth at roughly 1-10 nanometers per hour. Slow surface-to-bulk transport in viscous particles limits vapor uptake, while reduced volatility at lower temperatures enhances growth.
This buffering effect ensures that newly formed nanoparticles grow at remarkably similar rates, regardless of ambient conditions or the concentrations of condensable vapors, which can vary by orders of magnitude.
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