Are the drifting clouds truly heavy?

To the eye a cloud drifts as if weightless. Measured, a modest cumulus carries water by the hundreds of tonnes, and a single storm cumulonimbus by the hundreds of thousands — mass metered through radar reflectivity and droplet physics in the twentieth century. Against the appearance of weightlessness, the adjective the verse selects is thiqāl — heavy — and classical exegesis already read it as laden with water (7:57 uses the same description). The stamp covers the physical assertion: the clouds are, in fact, heavy.

[15] Rogers & Yau, A Short Course in Cloud Physics · al-Ṭabarī, Jāmiʿ al-bayān ad 13:12 · Q7:57