Sprites need a thunderstorm to be generated. Thus they will be observed over thunderstorms, especially over large and powerful ones. They have been observed over Europe, Japan and USA. However, because of the much higher lightning activity over Africa, Indonesia and South America, sprites will be observed in these regions when scientists will be able to mount sprite-watch systems there.

Because of their altitude, an observer will need to be far away from the thunderstorms, looking above those. An optimal distance is 150-200 km.

Sprites are likely to occur most at the end of thunderstorm. Not all thunderstorms will produce sprites, probably only those that are powerful and can charge the clouds gently, avoiding to loose all the energy in lightning flashes. However this is still a matter of debate.

The pictures in this page show three sprite events during a thunderstorm over South-East France. They occurred on the 11 August 2005, starting 22:44 UT at about 12 minutes interval. This interval could be a typical interval needed by the thunderclouds to recharge before it can produce new sprites. They were recorded by a low light level camera situated in central France on a top of a mountain (the Puy de Dome). The two first sprites are carrot shaped, the last is rather a column sprite. In the bottom part of the pictures you can notice dim lights of lightnings that illuminated the thunderclouds.

Enrico and Anna