Did you ever watch lightning in thunderstorms? Spectacular and scary at the same time, right? Why don't you watch above thunderstorms at night? You'll be surprised what you get to see: With a little bit of luck, you will be able to see lightning which goes from the top of the thundercloud up to 100 km height straight into space. But these lightning flashes, denoted sprites, are rather red and bluish, because they are happening in a different part of the atmosphere.

Because of the colour of sprites scientist name them also "red sprites". The colour is one of the reason why this is not very easy to see sprites by eye - it is much easier to notice something more bright than redish in the sky! The second reason is that sprites live for a very short time - the flashes last for much less than one second! That is why people use some equipment like a low light level camera to observe sprites.

The sprite lightnings are not only of different colour than the lightnings we observe from the ground during a thunderstorm, but they also have different shapes. Some sprites resemble a carrot: they are wide in the middle and becoming thinner at the bottom with some tendrils as if they have roots. And they also have something like leaves in the upper part! That is why they are called carrot sprites. There are also columnar sprites because they resemble a column: they are of almost the same width in the upper, middle and bottom part. And some sprites are difficult to classify as a carrot or column sprites - they could be different.

You can see sprites over large and powerful thunderstorms when strong atmospheric discharges are produced. You usually observe them as lightnings - bright channels of light from thunderstorm clouds to the ground, and a thunder - a wave of sound in the air. Sprites usually accompany a specific strong thunderstorm discharges but happen at heights about 50-90 kilometers above the ground while thunderstorm clouds are usually not higher than 5-10 kilometers above the ground.

Martin and Anna