Multistation observations of Schumann resonance (SR) intensity document common behavior in the evolution of continental‐scale lightning activity in two super El Niño events, occurring in 1997/98 and 2015/16. The vertical electric field component of SR at Nagycenk, Hungary and the two horizontal magnetic field components in Rhode Island, USA in 1997, and in 2014–2015, the two horizontal magnetic field components at Hornsund, Svalbard and Eskdalemuir, United Kingdom as well as in Boulder Creek, California and Alberta, Canada exhibit considerable increases in SR intensity from some tens of percent up to a few hundred percents in the transition months preceding the two super El Niño events. The UT time distribution of anomalies in SR intensity indicates that in 1997 the lightning activity increases mainly in Southeast Asia, the Maritime Continent and India, i.e. the Asian chimney region. On the other hand, a global response in lightning is indicated by the anomalies in SR intensity in 2014 and 2015. SR‐based results are strengthened by comparison to independent lightning observations from the Optical Transient Detector and the World Wide Lightning Location Network, which also exhibit increased lightning activity in the transition months. The increased lightning is attributable to increased instability due to thermodynamic disequilibrium between the surface and the midtroposphere during the transition. The main conclusion is that variations in SR intensity may act as a precursor for the occurrence and magnitude of these extreme climate events, and in keeping with earlier findings, as a precursor to maxima in global surface air temperature.

Oceanic lightning can be a sensitive indicator of aerosol effects on lightning characteristics as thermodynamic contrast is indistinct over adjacent oceanic regions. The study presents discernable aerosol impacts on lightning characteristics by analyzing 2 years (2017–2018) of intracloud (IC) and cloud‐to‐ground (CG) lightning data from Earth Networks Total Lightning Network over two key regions in southern South China Sea. Mean stroke density, IC/CG ratio, +IC fraction, and +CG fraction in polluted conditions are respectively 3.7, 2, 1.2, and 5.8‐fold larger than unpolluted counterparts. Total stroke contrast is further confirmed with the GLD360 network. Thermodynamic parameters conversely support slightly stronger convection over clean ocean. Clear evidence shows cloud droplet size diminishes with added aerosol. Aerosol invigorates more frequent and robust mixed‐phase development, endowing maritime convection with continental characteristics. Modifications in the charge reversal temperature and lower and upper positive charge regions are speculated on as means for stimulating more positive ICs and CGs.

Cavity optomechanical systems are being widely developed for precision force and displacement measurements. For nanomechanical transducers, there is usually a trade-off between the frequency (f_M) and quality factor (Q_M), which limits temporal resolution and sensitivity. Here, we present a monolithic cavity optomechanical transducer supporting both high f_M and high Q_M. By replacing the common doubly clamped, Si₃N₄ nanobeam with a tuning fork geometry, we demonstrate devices with the fundamental $f_M\approx 29\hspace{0.17em}\text{MHz}$ and $Q_M\approx 2.2\times {10}^5$ , corresponding to an f_MQ_M product of $6.35\times {10}^{12}\hspace{0.17em}\text{Hz}$ , comparable to the highest values previously demonstrated for room temperature operation. This high f_MQ_M product is partly achieved by engineering the stress of the tuning fork to be 3 times the residual film stress through clamp design, which results in an increase of f_M up to 1.5 times. Simulations reveal that the tuning fork design simultaneously reduces the clamping, thermoelastic dissipation, and intrinsic material damping contributions to mechanical loss. This work may find application when both high temporal and force resolution are important, such as in compact sensors for atomic force microscopy.

The 2019–2020 Australian wildfire crisis broke the historical bushfire record and heavily contaminated the continental and offshore atmosphere. This study found that lightning strokes increase considerably, by 73% over land and 270% over ocean, during the wildfire season. Thermodynamic parameters support a weaker forcing, unfavorable for frequent lightning activity over ocean. Clear augmentation of smaller cloud ice particles is identified with aerosol, while cloud liquid water path changes are feeble over ocean. Added aerosol invigorates positive intra‐cloud (IC) strokes and negative cloud‐to‐ground (CG) strokes in moist oceanic convection and facilitates a noticeable positive correlation between precipitation and lightning strokes. Rainfall events accompanied by lightning increase by 240% with added aerosol. Aerosol advected from land to ocean can lead to a larger hydrometeor concentration and smaller‐size ice crystals above the freezing level and thereby, invigorate convective strength systematically to stimulate more frequent and more robust mixed‐phase development, energizing the lightning discharge process.