How are human-made aerosols changing clouds?
Human-generated aerosol particles affect solar radiation by direct scattering and absorption, but also change cloud properties through particles acting as cloud condensation nuclei (CCN) and ice nuclei (IN), a pathway referred to as the “indirect aerosol effect.” This effect is likely the manifestation of two different aerosol-cloud interaction mechanisms. One encompasses aerosols’ effect on cloud water, specifically how a decrease in cloud particle size decreases precipitation efficiency, thereby increasing cloud lifetimes. Oreopoulos and Platnick study the other mechanism, called the Twomey effect, which involves the radiative effect of cloud microphysical changes only (no change in cloud water amount). Here the greater availability of CCN or IN yields clouds with more numerous but smaller cloud particles, and therefore larger optical thickness. The authors seek to quantify the spatial and temporal sensitivity of liquid clouds to the Twomey effect by studying data from NASA’s satelli
Human-generated aerosol particles affect solar radiation by direct scattering and absorption, but also change cloud properties through particles acting as cloud condensation nuclei (CCN) and ice nuclei (IN), a pathway referred to as the “indirect aerosol effect.” This effect is likely the manifestation of two different aerosol-cloud interaction mechanisms. One encompasses aerosols’ effect on cloud water, specifically how a decrease in cloud particle size decreases precipitation efficiency, thereby increasing cloud lifetimes. Oreopoulos and Platnick study the other mechanism, called the Twomey effect, which involves the radiative effect of cloud microphysical changes only (no change in cloud water amount). Here the greater availability of CCN or IN yields clouds with more numerous but smaller cloud particles, and therefore larger optical thickness. The authors seek to quantify the spatial and temporal sensitivity of liquid clouds to the Twomey effect by studying data from NASA’s satelli
