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The most powerful optical emissions from lightning have been described as “superbolts” since the 1970s. Holzworth et al. (2019, https://doi.org/10.1029/2019jd030975) recently applied the superbolt label to the most energetic Radio Frequency emissions recorded by the World Wide Lightning Location Network (WWLLN). We compare the WWLLN energies to optical measurements by the photodiode detector on the Fast On‐orbit Recording of Transient Events satellite and the Geostationary Lightning Mappers on NOAA's Geostationary Operational Environmental Satellites to assess whether these energetic WWLLN events coincide with optical superbolts. We find no overlap between optical and WWLLN superbolts. Moreover, extreme WWLLN events occur in a contrasting meteorological context to optical superbolts. Despite similarities in their overall global patterns of occurrence, WWLLN superbolts correspond to a different phenomenon. Plain Language Summary Where do the most powerful lightning signals on Earth come from? The answer depends on the wavelength of radiation being measured. There is a long history of using the flashes of optical light produced by lightning to make this assessment. These top cases are known as “superbolts” and typically arise from long‐horizontal discharges that we call “megaflashes,” which are highly effective light sources. A recent study by Holzworth et al. (2019, https://doi.org/10.1029/2019jd030975) used radio waves in the Very Low Frequency (VLF) band recorded by the World Wide Lightning Location Network (WWLLN) to assess lightning intensity. While they use the same superbolt terminology for their high energy VLF events, our comparisons with optical sensors show that they are a distinct phenomenon. These WWLLN superbolts come from small flashes in the thunderstorm core rather than megaflashes in outlying electrified cloud regions. Key Points Optical and World Wide Lightning Location Network (WWLLN) Very Low Frequency energies are compared in superbolt cases Optical superbolts are associated with large megaflashes typically found in stratiform clouds and do not reach the WWLLN 1 MJ threshold WWLLN superbolts do not produce strong optical flashes, and arise in convective thunderstorm cores with low flash rates

\"This book explores the application of Scalia's textualism and originalism to education law and reflects upon Scalia's teachings and his pedagogy. Education law may seem to be an odd vehicle for considering Scalia's constitutional approach, but thinking about schools requires attention to political fundamentals: freedom of speech, free exercise of religion, equality of opportunity, federalism, and the proper role of the expert. Legal scholars, philosophers, and political scientists provide both critiques and apologies for Scalia's approach\"--Back cover.

The most intense thunderstorms on Earth were surveyed using the comprehensive meteorological instrumentation on the Tropical Rainfall Measuring Mission (TRMM) satellite. Expansive land‐based Mesoscale Convective Systems (MCSs) were consistently identified among the Earth's most intense thunderstorms, with their organization into many convective cells spanning a large areal extent permitting exceptional overall flash rates for these storms. In this study, we identify a new class of extreme thunderstorm. Lightning‐dense thunderstorms are relatively compact convective storms whose concentrated lightning activity hinders our ability to accurately measure their flash rates. The top storms have a flash rate of one flash spanning many seconds, as there is insufficient separation to distinguish one flash from another. While any particularly active convective cell could be capable of producing high lightning densities, we find that thunderstorms with the greatest lightning densities on Earth are found in maritime thunderstorms that have not been appreciated in prior work due to the inaccurate flash rate measurements. These storms that are mostly found throughout the Gulf of Mexico and east of South Africa (among other coastal and oceanic regions) have measured TRMM proxies for convective intensity that rival the top MCS thunderstorms, but their horizontal and vertical dimensions are small by comparison. Thus, the necessary microphysical elements for electrification processes are more highly concentrated, enabling the observed extreme lightning densities. Plain Language Summary Using lightning flash rates as a measurement of thunderstorm intensity is complicated by the fact that thunderstorms produce lightning in different ways based on how they are organized. Isolated thunderstorms might consist of a single convective cell with all of the measured lightning coming from that one cell. Meanwhile, a Mesoscale Convective System (MCS) moving across the central United States would be comprised of many convective cells across a line spanning up to thousands of kilometers. All of the flashes produced by all of the cells count toward the total flash rate of the organized MCS. Due to this advantage, studies that assess the highest flash rate thunderstorms on Earth identify MCSs as their top storms. In this study, we ask a different but related question: where are the thunderstorms with the greatest lightning densities on Earth? Answering this question allows us to identify particularly active convection regardless of whether it describes an isolated thunderstorm or one of the cells in a broader MCS. We find that the storms with the greatest lightning densities are not organized MCSs over land, but rather smaller maritime thunderstorms. Key Points Certain intense thunderstorms produce extraordinary amounts of lightning concentrated in one area Lightning‐dense thunderstorms are comparable in intensity to the top flash rate storms over land, but are smaller maritime storms Measured flash rates are inaccurate for these lightning‐dense thunderstorms, adversely impacting weather forecasting and physical research

It is important to understand connections between society and the natural environment for anticipating hazards and anthropogenic effects on the Earth system. In this study, we conduct a detailed exploration of interactions between oceanic thunderstorms and maritime traffic. Shipping traffic produces aerosols that perturb the otherwise “clean” ocean environment. Prior work proposed these aerosol effects as the cause of increased lightning over certain shipping lanes. However, introducing tall grounded objects into a high electric field environment might also facilitate lightning discharges, as we see with upward lightning over land. We consider both possibilities. Our analyses of the thunderstorms responsible for enhanced lightning activity over the shipping lane with the clearest anthropogenic signal indicate that the enhancement results from an increased frequency of lightning‐producing storms. Observed variations in thunderstorm microphysics between the shipping lane and nearby oceans are small compared to natural factors such as the Indian monsoon, and are on the same scale as the local variability in the data. By contrast, matching lightning stroke data with ship transponder events in oceanic regions where public data are available reveals a strong signal from direct ship interactions. Lightning is 15× (66×) more likely to occur at a ship location compared to 2 km (25 km) away. These results highlight the central role of direct ship interactions in explaining lightning enhancements over shipping lanes. We also document the frequency of these direct lightning interactions across various categories of vessels and on individual ships present in the public data. Plain Language Summary It was previously shown that there is more lightning over certain shipping lanes compared to the surrounding oceans. These enhancements were attributed to pollution from shipping traffic making it easier for thunderstorms to intensify. However, tall objects in high electric field environments are also known to initiate lightning. An alternate scenario that should contribute to the lightning enhancement is tall well‐grounded ships facilitating lightning production—particularly in storms that are near the tipping point between remaining Electrified Shower Clouds (ESCs) that lightning sensors cannot detect and producing lightning to become detectable thunderstorms. Our analyses indicate that the differences between the thunderstorms over the shipping lane with the most pronounced lightning enhancement and nearby oceanic regions are small compared to natural local weather patterns. Trends are difficult to confirm because they are on the same magnitude as the noise in the satellite data. The enhancement arises because there are simply more thunderstorms over the shipping lane compared to the nearby oceanic regions. Moreover, directly matching lightning strokes with ship positions provides clear evidence of lightning enhancements at the ship location from direct interactions with the vessel. Key Points Lightning enhancements over shipping lanes are accompanied by more thunderstorms without pronounced evidence of storm invigoration Lightning over maritime routes preferentially occurs close to current ship positions compared to other nearby locations surrounding the ship Direct ship interactions, aerosol effects, and local weather patterns are all important for understanding lightning enhancements

We previously observed that long‐horizontal lightning flashes exceeding 100 km in length, known as “megaflashes,” occur preferentially in certain thunderstorms. In this study, we develop a cluster feature approach for automatically documenting the evolutions of thunderstorm systems from continuous lightning observations provided by the Geostationary Lightning Mapper (GLM) on NOAA's Geostationary Operational Environmental Satellites (GOES). We apply this methodology to GOES‐16 GLM observations from 2018 to mid‐2022 to improve our understanding of megaflash‐producing storms. We find that megaflashes occur in long‐lived (median: 14 hr) storms that grow to exceptional sizes (median: 11,984 km2) while they propagate across long distances (median: 622 km) compared to ordinary storms. The first megaflashes are typically produced within 15 min of the storm reaching its peak intensity and extent. However, most megaflashes occur ≥13 hr after the initial megaflash activity, and are sufficiently close to convection to suggest initiation in the thunderstorm core (where GLM has difficulty detecting faint early light sources from megaflashes). Megaflashes generated outside of convection are rare, accounting for 2.7% of the sample using a 50 km convective distance threshold, but also tend to be larger than normal megaflashes, possibly due to having direct access to electrified stratiform clouds through which megaflashes propagate. Plain Language Summary Long‐horizontal “megaflashes” that exceed 100 km across are now being routinely detected across the Americas by NOAA's Geostationary Lightning Mappers (GLMs). Initial studies on where/when megaflashes arise have shown that these exceptional flashes preferentially occur in certain storms. In this study, we develop a methodology to automatically identify megaflash‐producing thunderstorms and track them over time. We apply it to GOES‐16 GLM observations to investigate the types of storms capable of generating lightning at the megaflash scale. We find that megaflashes are produced by storms that grow to large sizes over long periods, and these storms can generate megaflashes over many hours. Most of these megaflashes appear to originate from the convective line, but the small numbers of megaflashes generated deep within the stratiform region tend to be larger. These findings are consistent with our understanding of the life cycle of megaflash‐producing Mesoscale Convective Systems. Key Points Megaflashes are produced by Mesoscale Convective Systems (MCSs) that grow large electrified stratiform cloud regions over many hours We developed a methodology to track thunderstorm systems, including those that produce megaflashes, and applied it to 4 years of data Megaflash timing statistics reflect the life cycle of MCSs—with megaflash onset accompanying peak storm sizes/flash rates

Space‐based optical lightning sensors including the lightning imaging sensor (LIS) and geostationary lightning mapper (GLM) are pixelated imagers that detect lightning as transient increases in cloud top illumination. Detection requires optical emissions to escape the cloud top to space with sufficient energy to trigger a pixel on the imaging array. Through scattering and absorption, certain clouds are able to block most light from reaching the instrument, causing a reduction in detection efficiency (DE) and possibly location accuracy (LA). Radiant lightning emissions that illuminate large cloud top areas are used to examine scenarios where clouds block light from reaching orbit. In some cases, these anomalies in the spatial radiance distribution from the lightning pulse lead to “holes” in the optical lightning flash where certain pixels fail to trigger. Such holes are identified algorithmically in the Tropical Rainfall Measuring Mission satellite LIS record and the microphysical properties of the coincident storm region are queried. We find that holes primarily occur in tall (IR Tb < 235 K) convection (87%) and overhanging anvil clouds (10%). The remaining 3% of holes occur in moderate‐to‐weak convection or in clear air breaks between stormclouds. We further demonstrate how an algorithm that assesses the spatial radiance patterns from energetic lightning pulses might be used to construct an optical transmission gridded stoplight product for GLM that could help operators identify clouds with a potentially reduced DE and LA. Plain Language Summary Lightning sensors on satellites detect lightning by looking at how they illuminate the surrounding clouds. These instruments register lightning events by comparing high‐speed movies of cloud top brightness with the comparably steady‐state background. However, there are some cases where the cloud is able to block the light produced by lightning from passing through. If too little energy makes it to the top of the cloud, the instrument will not be able to differentiate the lightning illumination from the background—and the lightning will not be detected. This study examines how clouds are illuminated by lightning to identify scenarios where light is blocked from reaching the LIS instrument. LIS “holes” are compared with the meteorological measurements from the other sensors on the Tropical Rainfall Measuring Mission satellite to investigate what types of clouds can inhibit lightning detection. We find that it is not just the tall thunderclouds that are responsible for holes in optical flashes, but also overhanging anvil clouds, and even breaks in the clouds surrounding the thunderstorm. These insights might be used to construct a gridded stoplight product that can alert end users to issues with optical transmission. Key Points Certain clouds block optical lightning emissions from reaching orbit, which can lead to missed lightning detections Poorly transmissive clouds modify the spatial energy distribution of large and bright optical pulses—in some cases creating holes These anomalies in the spatial radiance data are used to identify poorly transmissive clouds in the lightning imager observations