The sight of a sandworm of Arrakis (Shai-Hulud) breaching the surface is usually accompanied by lightning. Is there any explanation given for this phenomenon?
Is it supposed to be due to accumulation of electric charge from the friction between the moving sandworm and the sand (like a Van de Graaff generator)? Or is it caused by some other feature of the sandworm, the environment of Arrakis, or even the spice?
Furthermore, a high electric potential between two separate regions must exist for a lightning discharge. If the sandworm is one of these regions, what is the other region? For example, does the desert planet Arrakis have suitable clouds for lightning discharges between a cloud and a charged sandworm that breaches the surface of the isolating sand?