There is one easy solution, but the results are "average"...

1. Create a dark cloudy atmosphere
2. Load a "large dead tree" from the plants collection.
3. Turn it upside down and make it really big.
4. change the material to "luminous glow".
5. adjust the color and the glow intensity of the material.
6. add spot lights to create a more dramatic effect.

And it's done ! an "average" lightning...

Eric