This daring compound adjective, from a phrase cited in derision by Aristophanes' character Strepsiades in Clouds (335; cf. all scholia, editors and translators ad loc.), represents well the style of the 'new dithyramb' (delta 1029, kappa 2647, alpha 1810, epsilon 1174), which was criticised by the comic playwrights, and by Dionysius of Halicarnassus (De compositione verborum 19, p.152-54 Usher [1985 Loeb edition]) and Philostratus the Roman (kappa 912), among others. The second part of the adjective is a rare word ai)/glh (alphaiota 64) for various sorts of 'brilliance, brightness', for example, of the rays of the sun. The first part is from the (usually) passive verbal adjective (Smyth, Greek Grammar §472) from stre/fw 'turn around, spin, twist, braid; turn back, turn over, reverse' (web address 1), strepto/s. This verbal adjective means 'spun, plaited, braided, turned, twisted', and was used for the bracelets and collars made of plaited gold (web address 2). In the context the compound represents the intertwining motion of advancing stormclouds, refracting or not the sun's rays in red, orange and black as well as white. As elsewhere, the language of new dithyramb is meant to reinforce the choreography and costumes of the dancers and the music; cf. theta 475. Here it would invoke a choreography and costuming of dancers in different brilliant colors advancing in interweaving movements giving the impression of the braiding of colored threads. D.A. Campbell in his edition of Philoxenus (Greek Lyrics vol. 5.171) suggests "twist-flashing." LSJ has "whirling-bright" (web address 3).
The form of the adjective has posed a number of problems to grammarians, scholiasts, editors and translators. It is a feminine, rare for a compound adjective, from an unusual masculine in -as (see Dover's edition of Clouds, p.146). It may be accusative agreeing with o(rmh/, or genitive plural with the same ending -a=n as nefela=n. This Suda entry (almost identical with the scholia ad loc.) asserts that the adjective means something very different from what it is intended to mean, i.e. is a malapropism for a different word. We would thus be in search for two different meanings. The entry assumes in the last sentence that the word is intended to mean "turning back and obscuring the bright rays of the sun". This would require the causative prefix streps- from the same verb, cf. streyodike/w 'pervert justice', streyodikopanourgi/a 'cunning in perverting justice' (Aristophanes, Clouds 434, Birds 1468); it would be an image from wrestling (see examples in J. Taillardat, Les Images d'Aristophane (1965) 335ff.). The word actually used would have to be the malapropism for this meaning. This might explain some of the curious translations of the given word. Dover (pp. 145-46) takes the compound to mean 'a collar or bracelet (another meaning of ai)/glh, LSJ II, web address 4) of twisted metal' as a metaphor for the zigzag lightning flashing between stormcloud and earth. Similarly W.M. Starkie (1966 edition) translates it "flashing with crisped fire"; J. Henderson (1998 Loeb edition) writes "dire downdraft of humid clouds zigzaggedly braceleted".
It is useful to read the passage in context (lines 335-43, web address 5). The character Strepsiades is watching the arrival of the Clouds as chorus of the play, and expressing his surprise to learn that they were the real authors of high-flying phrases such as the ones he quotes. At line 343 they seem to him "like spread out threads (perhaps balls or skeins) of wool." The metaphor of wool for clouds was also appropriate in our phrase, for the verb stre/fw is used both of spinning wool and of twisting thread in carpet- and cloth-making. Storm clouds with their bright colors are indeed like great strands of brightly colored, fluffy wool braided in a giant carpet. How were the Chorus of Clouds costumed? Like fluffy balls of wool? Why not? In what way then did the costume and choreography of the Chorus of Aristophanes' comedy differ from those of the dithyrambic chorus?
[1] In the discussion I accept the alternative reading streptaigla=n.
[2] Philoxenus of Cythera (phi 393; RE 20.192-94 'Philoxenus [23]'.) was not the author of the phrase quoted in Clouds, first produced in 423 when he was 11 or 12 years old and revived when he was still a teenager. Aristophanes parodies his Cyclops at Plutus 290ff. (epsilon 336, theta 475), but he was excluded by Antiphanes (fr.207 PCG vol. 2) from the worst excesses of the new style (cf. delta 1029, kappa 2647). The remains of his literary work and the testimonia are given in D.L. Page, Poetae Melici Graeci §§814-35 (pp. 423-32) and D.A. Campbell, Greek Lyric [LCL] v.5 pp.176-197. For his famous piper Antigenides see alpha 2657. His colorful character and history are mentioned several times in Athenaeus. Most famous is the story of how he was sent to the Syracusan stone-quarries for criticizing the writing of the tyrant Dionysius I of Syracuse and, when later rehabilitated and asked once more to give his verdict, he cried, "Take me back to the quarries!" (alpha 2862, delta 1178, epsiloniota 291). Athenaeus (8.341A-D) reports a story from the Anecdotes (Chreiai) of Machon (ed. Gow, fr.9.64ff., cf. 10.87ff.) that he made himself sick by eating a large octopus. He is, however, probably not the same as the notorious glutton Philoxenus son of Eryxis (RE 20.190 'Philoxenus [5]'). To make things worse, the poet Philoxenus of Leucas (phi 395; Campbell 138-75; RE 20.194 'Philoxenus [24]'), wrote The Banquet, apparently referred to by the comic playwright Plato (fr.198.4 PCG vol. 7) as a cookbook. On the uncertain distinction between these men see Campbell's edition (pp. 177-79) and Gow's note (pp. 75-80).
[3] The reading in the text here in the scholia and Suda a)hdi/an 'unpleasantness' is certainly a mistake for the word a)/deia, 'fearlessness, daring', which is used for poetic licence by Dionysius of Halicarnassus (De compositione verborum 19), precisely in a discussion of Philoxenus and others, and is a common term in Apollonius Dyscolus (but always with the adjective "poetic" or "comic", cf. Himerius, cited in LSJ 2, web address 6). Cinesias in Aristophanes' Birds (1375, see Dunbar's note) says that he "is seeking a new path with fearless (a)fo/bw|) mind and body."