經律異相 1.100

1.100

虛空雲中。有時地大與水相觸。有時與火風等大相觸。水火風大更互相觸。皆生虛空雲中雷聲（出長阿含經第二十卷）。

In the clouds of the open sky, sometimes the earth element clashes with water, and sometimes it clashes with elements like fire and wind. The elements of water, fire, and wind also clash with one another; all of them produce the sound of thunder in the clouds of the open sky. (From the Dīrgha-āgama, fascicle 20.)