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Lightning is one of the main sources of NOx in the Earth's atmosphere. However, there is a large variability in NOx production during the lifetime of thunderstorms. In this study, we used the TROPOspheric Monitoring Instrument (TROPOMI) cloud and NO2 research products along with Lightning Mapping Array (LMA) measurements to investigate the possible relation between the amount of NOx produced per lightning flash and flash channel length in the Ebro Valley. We found that there is a positive relationship between both variables. In turn, the vertical structure of the analyzed lightning flashes indicates that longer flashes could release more LNOx at lower altitudes than shorter flashes, while higher flash rates produce less LNOx per flash. Plain Language Summary: Lightning produces significant amounts of NOx in the Earth's atmosphere. However, the quantity of NOx generated during thunderstorms exhibits significant variation. In this study, we used a space‐based instrument called TROPOMI to look at clouds and measure NO2, and we also used a network of antennas called Lightning Mapping Array to map the spatial structure of lightning strikes. Our main goal was investigating if there is a connection between the amount of NOx produced by lightning and how long the lightning flashes were in the Ebro Valley. We found that there is a positive relationship between the two variables. We also looked at the structure of the lightning flashes and found that longer flashes release more NOx at lower altitudes compared to shorter flashes. Additionally, when there are more frequent lightning flashes, each flash produces less NOx. Key Points: Lightning Mapping Array data reveals a positive correlation between lightning NOx production efficiency and the lightning flash lengthsThe investigation of space‐based data demonstrates a negative correlation between lightning NOx production efficiency and flash frequencyMean NOx per flash length obtained in this work vary between 1.9 × 1021 and 3.8 × 1021 molec NOx/m [ABSTRACT FROM AUTHOR]

Lightning flashes are an important source of wildfires worldwide, contributing to the emission of trace gases to the atmosphere. Based on experiments and field observations, continuing currents in lightning have since a long time been proposed to play a significant role in the ignition of wildfires. However, simultaneous detections of optical and radio signals from fire‐igniting lightning confirming the role of continuing currents in igniting wildfires are rare. In this work, we first analyze the optical signal of the lightning‐ignited wildfires reported by the Geostationary Lightning Mapper over the Contiguous United States (CONUS) during the summer of 2018, and we then analyze the optical and the Extremely Low Frequency signal of a confirmed fire‐igniting lightning flash in the Swiss Alps. Despite data uncertainties, we found that the probability of ignition of a lightning flash with Continuing Current (CC) lasting more than 10 ms is higher than that of cloud‐to‐ground lightning in CONUS. Finally, we confirm the existence of a long CC (lasting about 400 ms) associated with a long‐lasting optical signal (lasting between 2 and 4 s) of a video‐recorded fire‐igniting lightning flash. Plain Language Summary: Lightning plays a significant role in causing natural fires. Previous studies have found that a specific type of lightning, known as continuing current lightning (CC), has a higher likelihood of igniting fires. CC lightning refers to a phenomenon where electrical charge continues to flow through the channel for extended periods of tens or hundreds of milliseconds, possibly leading to elevated vegetation temperatures. In our research, we used the optical lightning detections provided by the Geostationary Lightning Mapper to estimate the probability of wildfires associated with both normal lightning and CC lightning across the United States. To gain further insights, we employed a ground camera video and analyzed extremely low‐frequency radio signals to meticulously examine the duration of CC in a lightning strike that ignited a fire in the Alps. The findings of our study demonstrate that the probability of fire occurrence is higher when CC lightning is involved compared to typical lightning strikes. This highlights the importance of understanding the characteristics of lightning and its varying impacts on fire risk assessment. Key Points: The probability of wildfire ignition by cloud‐to‐ground lightning is larger for flashes with Continuing Current (CC)The variation of the lightning ignition efficiency of lightning with CC suggest a significant influence of other factorsThe analysis of one single lightning‐ignited fire in the Alps confirms the presence of a lightning with a long CC [ABSTRACT FROM AUTHOR]

A three‐stage simulation is used to explore the chemical influence of low altitude (50 km) sprite streamers on the atmosphere, including the chemical trail after the streamer has faded away. In the first stage (streamer phase) a 2D electrodynamical streamer model quantifies the generation of NOx and N2O, and the removal of ozone (O3) by a downward propagating streamer during Δtstreamer = 80 μs. This streamer propagation leads to a distinctive region in the streamer channel, the glow, where the electric field is enhanced. In the second stage (glow phase), the computed densities of the first stage are used as initial conditions for a 0D model to study the chemical evolution of the streamer channel, where we assume a remanent field of 100 Td for the glow and 0 Td elsewhere. This stage lasts Δtglow = 85 μs, the typical glow lifetime at 50 km. Finally, in the third stage (post‐streamer phase), we use the same 0D model, switch off the field in the glow region and let the whole streamer wake evolve roughly 100 s (100 s − Δtglow). Results show a key species such as O3 is mainly depleted during the streamer phase while NOx and N2O are predominantly produced during the same phase. We also compute the local increase of NO2 by sprite streamers at ∼50 km and find out that it could account for the measurable NO2 anomaly over thunderstorms reported from satellite‐based measurements. Plain Language Summary: Sprites are high‐altitude electric discharges that occur above thunderstorms and span tens of kilometers vertically and hundreds of meters horizontally. They are made of hundreds of fast‐propagating plasma filaments known as streamers. These streamers propagate due to an enhanced electric field at its tip that ionizes the air ahead, leaving behind a chemical trail in the atmosphere. In this work, we focus on the production/removal of prominent greenhouse gases such as N2O or O3 as well as nitrogen oxides accounting for the measurable impact of sprites on the low‐mesosphere chemistry as reported by satellite‐based measurements. Key Points: A three‐stage approach is proposed to explore the chemical impact of sprite streamers at 50 kmThe main mechanism leading to N2O is associative detachment during the streamer phase and N + NO2 − >N2O + O in the long post‐streamer phaseThe local increase of NO2 due to sprite streamers at ∼50 km could account for the measurable chemical perturbation of NO2 over thunderstorms [ABSTRACT FROM AUTHOR]