AGU: Geophysical Research Letters

 

Editors' Highlight

Sprite photon emission rates

Sprites are short-lived optical events that occur in the mesosphere and lower ionosphere above electrically active thunderstorms. New observations of sprites with submillisecond time resolution, collected by Stenbaek-Nielsen et al. (2007), have shown that many structures seen in video image sequences, such as branches and tendrils, actually are small but very bright streamer heads moving up and down at velocities of about 0.1 times the speed of light. The brightness in the images is up to 5 times that of Venus, the otherwise brightest object in the sky besides the Sun and the Moon. Because their physical size is less than the spatial resolution in the images, the authors used theoretical models for streamer head development and volume emission rates and inferred their size to be 10–100 m. Such bright objects have not been recognized before; they last less than 1 ms and have been detectable only with newly available high frame rate cameras. The observations were collected in 2005 from the Langmuir Laboratory, New Mexico.

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