Tracking raindrops, one molecule at a time

Science Daily  October 25, 2022 A team of researchers in the US (U Mass. Amherst, University of Alaska) studied the mechanisms of precipitation deuterium excess (d-excess) seasonality in low-latitudes and mid-latitudes through a new analysis of precipitation isotope databases along with climate reanalysis products and moisture tracking models. The ultimate d-excess signals are produced after complex modulations by several reinforcing or competing processes. They developed a simple seasonal water storage model to show that contributions of previously evaporated residual water storage and higher transpiration fractions may lead to relatively low d-excess in evapotranspiration fluxes during periods of enhanced continental moisture […]

Light amplification accelerates chemical reactions in aerosols

Science Daily  April 14, 2022 Researchers in Switzerland reported that optical confinement could create spatial structuring of the light intensity inside the particle and thereby cause corresponding variations of photochemical rates. They probed single iron(III)–citrate particles using the iron oxidation state as a photochemical marker. Based on the results, they predicted an overall acceleration of photochemical reactions by a factor of two to three for most classes of atmospheric aerosol particles. Rotation of free aerosol particles and intraparticle molecular transport generally accelerate the photochemistry. According to the researchers, given the prevalence of optical confinement effects, their influence on aerosol particle […]