The works of Ādi Śaṅkarācārya

Chāndogyopaniṣadbhāṣyam

Verse 244

पर्जन्यो वाव गौतमाग्निस्तस्य वायु-रेव समिदभ्रं धूमो विद्युदर्चिरशनिरङ्गाराह्रादनयो विस्फुलिङ्गाः ॥ १ ॥

In plain words

The rain cloud itself is the fire taught to Gautama. The wind is its fuel, the cloud its smoke, the lightning its flame, the thunderbolt its glowing coals, and the thunderous roar its flying sparks.

Close to the Sanskrit

The rain cloud indeed is the fire of Gautama, of that the wind alone is the fuel, the cloud is the smoke, the lightning is the flame, the thunderbolt the embers, the rumbling sounds the sparks.