The altar is Parganya (the god of rain), O Gautama; its fuel is the air itself, the smoke the cloud, the light the lightning, the coals the thunderbolt, the sparks the thunderings.

In plain words: The second fire is Parjanya, the god of rain. The air is its fuel and the cloud its smoke. Lightning is its light, the thunderbolt its coals and the rumbling thunder its sparks.