The Clouds (Ancient Greek: Νεφέλαι) is a comedy by Aristophanes, originally produced in 423 BC. The play satirises the philosophical scene in Athens, featuring Socrates as a central character. In direct contradiction to the later dialogues of Plato and Xenophon, Aristophanes portrays Socrates as interested in physical rather than ethical questions, and as teaching rhetoric for money like the sophists.
Free online texts
Gutenberg: The Clouds, translated by W.J. Hickie, multiple formats.
Internet Archive: The Comedies of Aristophanes, Vol I - The Acharnians, Knights, Clouds, Wasps, Peace and Birds, translated by W.J. Hickie. Multiple formats.
Internet Archive: The Clouds, Greek text edited with notes by Lewis Forman (1915). Multiple formats.
Internet Classics Archive: The Clouds. HTML and TXT formats.
Loebulus: Aristophanes I: Acharnians. Knights. Clouds. Wasps. PDF of public domain Loeb edition.
University of Adelaide: The Clouds, multiple formats.
BBC In Our Time: Comedy in Ancient Greek Theatre, Discussion with Melvyn Bragg and guests Paul Cartledge, Edith Hall and Nick Lowe.
History of Ancient Greece: o54- Old Comedy and Aristophanes. Podcast by Ryan Stitt.
History of Philosophy without any gaps: Socrates without Plato, podcast by Peter Adamson.
Librivox: The Clouds, public domain audiobook.
Literature and History: The Great Thundercrap Aristophanes' The Clouds - podcast and transcript by Doug Metzger.
National Theatre: An Introduction to Greek Comedy and Satyr Drama - video, featuring Edith Hall, Sean McEvoy, Alan Sommerstein, Laura Swift.
Wikipedia: The Clouds.
The Great Conversation: Further reading at Tom's Learning Notes
Plato: The Symposium - includes a speech by Aristophanes.
Ancient Greek resources: Learn to read Greek classics in the original.
Bloom's Western Canon: The Clouds is listed.