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Aerosol effects on the lightning intensity and polarity of a continental supercell storm were investigated using a three‐dimensional lightning scheme within the Weather Research and Forecasting model. We find that both intra‐cloud (IC) and cloud‐to‐ground (CG) flashes are enhanced by the increasing number of cloud condensation nuclei (CCN), especially the percentage of positive CG (+CG) strokes peaking at 42%. Electrical characteristics of the storm varied in different aerosol scenarios through microphysical processes. Added aerosols increase the number of cloud droplets and ice‐phase hydrometeors. The greater ice‐crystal concentration and larger graupel size ensure sufficient charge separation, leading to higher charge density and more lightning discharges. In addition, an inverted polarity charge structure with a strong positive‐charge region in the mid‐levels was formed mainly due to the positively charged graupel in the presence of higher supercooled cloud water content. Positive lightning channels originating from this positive‐charge region propagated to the ground, producing more +CG strokes. When the aerosol concentration was low, the charge density in the upper positive‐charge region was much lower due to smaller ice‐particle content. Consequently, there were barely any +CG strokes. Most of the negative CG flashes deposited positive charge in the lower negative‐charge region. Plain Language Summary: The possible effects of aerosols on lightning intensity and polarity were investigated using an explicit lightning scheme within a weather forecast model. Added aerosols invigorated intra‐cloud flashes and cloud‐to‐ground (CG) flashes in continental convection. A noticeably high fraction of positive CG lightning was also identified under polluted conditions. Elevated cloud condensation nuclei concentration increased the ice particle content and graupel size, leading to enhanced charge separation and lightning activity. An inverted‐polarity charge structure appeared owing to the positively charged graupel in the presence of greater supercooled cloud water amounts. This charge distribution was manifested in the lightning activity, showing that positive channels propagated to the ground, generating more positive CG strokes under polluted conditions. Key Points: Aerosols enhance charge separation and lightning discharges due to a greater ice‐crystal concentration and larger graupel sizeAerosols lead to inverted charge structure with strong positive‐charge region, producing high percentage of positive cloud‐to‐ground strokesGraupel particles gain positive charge at upper levels in the presence of higher supercooled cloud water under polluted conditions [ABSTRACT FROM AUTHOR]

Lightning is affected by many factors, many of which are not routinely measured, well understood, or accounted for in physical models. Several commonly used machine learning (ML) models have been applied to analyze the relationship between Atmospheric Radiation Measurement (ARM) data and lightning data from the Earth Networks Total Lightning Network (ENTLN) in order to identify important variables affecting lightning occurrence in the vicinity of the Southern Great Plains (SGP) ARM site during the summer months (June, July, August and September) of 2012 to 2020. Testing various ML models, we found that the random forest model is the best predictor among common classifiers. When convective clouds were detected, it predicts lightning occurrence with an accuracy of 76.9 % and an area under the curve (AUC) of 0.850. Using this model, we further ranked the variables in terms of their effectiveness in nowcasting lightning and identified geometric cloud thickness, rain rate and convective available potential energy (CAPE) as the most effective predictors. The contrast in meteorological variables between no-lightning and frequent-lightning periods was examined for hours with CAPE values conducive to thunderstorm formation. Besides the variables considered for the ML models, surface variables and mid-altitude variables (e.g., equivalent potential temperature and minimum equivalent potential temperature, respectively) have statistically significant contrasts between no-lightning and frequent-lightning hours. For example, the minimum equivalent potential temperature from 700 to 500 hPa is significantly lower during frequent-lightning hours compared with no-lightning hours. Finally, a notable positive relationship between the intracloud (IC) flash fraction and the square root of CAPE (CAPE) was found, suggesting that stronger updrafts increase the height of the electrification zone, resulting in fewer flashes reaching the surface and consequently a greater IC flash fraction. [ABSTRACT FROM AUTHOR]

Aerosols have significant and complex impacts on regional climate in East Asia. Cloud‐aerosol‐precipitation interactions (CAPI) remain most challenging in climate studies. The quantitative understanding of CAPI requires good knowledge of aerosols, ranging from their formation, composition, transport, and their radiative, hygroscopic, and microphysical properties. A comprehensive review is presented here centered on the CAPI based chiefly, but not limited to, publications in the special section named EAST‐AIRcpc concerning (1) observations of aerosol loading and properties, (2) relationships between aerosols and meteorological variables affecting CAPI, (3) mechanisms behind CAPI, and (4) quantification of CAPI and their impact on climate. Heavy aerosol loading in East Asia has significant radiative effects by reducing surface radiation, increasing the air temperature, and lowering the boundary layer height. A key factor is aerosol absorption, which is particularly strong in central China. This absorption can have a wide range of impacts such as creating an imbalance of aerosol radiative forcing at the top and bottom of the atmosphere, leading to inconsistent retrievals of cloud variables from space‐borne and ground‐based instruments. Aerosol radiative forcing can delay or suppress the initiation and development of convective clouds whose microphysics can be further altered by the microphysical effect of aerosols. For the same cloud thickness, the likelihood of precipitation is influenced by aerosols: suppressing light rain and enhancing heavy rain, delaying but intensifying thunderstorms, and reducing the onset of isolated showers in most parts of China. Rainfall has become more inhomogeneous and more extreme in the heavily polluted urban regions. Key Points: East Asia has suffered heavy aerosol loading of diverse propertiesStrong absorbing aerosols lower the boundary layer, suppress convection, and worsens air pollutionThe joint effects of aerosol on radiation and clouds alter the development of clouds and precipitation and regional climate [ABSTRACT FROM AUTHOR]

The molecular structure of the polymer PM6 is elaborately modified through random copolymerization by incorporating simple units of either difluoro‐substituted thiophene (2FT) or dicyano‐substituted thiophene (2CNT). The incorporation of the 2FT unit significantly enhanced the coplanarity of the random copolymers, leading to improved molecular crystallinity, whereas the introduction of the 2CNT unit featured the opposite effect. Thanks to the optimized morphology resembling a fiber‐like interpenetrating network structure, the organic solar cells based on PM6‐10%2FT:IT4F showed higher and more balanced charge mobilities, achieving a power conversion efficiency (PCE) of 12.65%, which is comparable to that of PM6‐based devices. For comparison, the 2CN‐series random copolymers‐based devices exhibited lower PCEs of ˂12%. Interestingly, a superior PCE close to 19.0% is achieved in PM6:L8‐BO:PM6‐20%2CN based ternary device due to the significant improvement in open‐circuit voltage. This work demonstrates that the crystallinity of donor polymers can be enhanced by introducing simple structural units to strengthen the coplanarity of the backbone, thereby achieving an optimized morphology that promotes favorable charge transport. [ABSTRACT FROM AUTHOR]