LAUSR

This work investigates the strongest optical emissions associated with long laboratory sparks (at the wavelengths of 337 and 777 nm) with the aim to understand similar emissions in lightning. The processes of the long‐spark formation are studied by using optical measurements, current signatures, and short‐time exposure images. Blue optical emissions (337 nm) are associated with streamer development and negative leader stepping, and the optical pulses have good correlation with current pulses. Red optical emissions (777 nm) are mainly associated with stable leader propagation, when this irradiance is predominant over the blue one. The results indicate that formations of stems from positive leaders also produce emissions at 777 nm. This work aims to support satellite‐based measurements that perform optical measurements in the same wavelength ranges.