Many floating bodies come together suddenly,
Rather rough in texture, so that they can cling, despite
The fact that bonds among the particles of cloud are slight.
The seeds combine together to make cloudlings first, and these
Catch onto one another, accumulating by degrees,
And driven by the wind in racks, they gather in a swarm,
Until the point when they build up into a raging storm.
– Lucretius, “De Rerum Natura,” 50 BCE (trans. by A. E. Stallings, 2007)