The "matutinal cloud" that Stephen and Bloom saw "from two different points of observation" at about the same moment (Stephen in Telemachus, Bloom in Calypso) covered the sun, but it was small. By the time represented in Oxen of the Sun it has covered the sky and unleashed a downpour, whose thunderclaps have terrified Stephen by making him think of divine judgment. Ithaca confirms that association in Stephen's mind by saying that the morning cloud was "at first no bigger than a woman's hand"; the image evokes a biblical expression of the coming wrath of God.
In chapter 17 of the first book of Kings, the prophet Elijah announces a drought whose effects will punish the wicked king Ahab. In chapter 18, after years of famine, God calls off the terrible drought and sends rain. Elijah sends his servant to look toward the sea, and the servant (after six unsuccessful tries) tells him, "there ariseth a little cloud out of the sea, like a man's hand. And he [Elijah] said, Go up, say unto Ahab, Prepare thy chariot, and get thee down, that the rain stop thee not. And it came to pass in the mean while, that the heaven was black with clouds and wind, and there was a great rain" (18:44-45).
While Stephen attributes his collapse in the brothel to this malignant divine agency, Bloom sees it as the result of "gastric inanition and certain chemical compounds of varying degrees of adulteration and alcoholic strength, accelerated by mental exertion and the velocity of rapid circular motion in a relaxing atmosphere," i.e. the mad whirling dance that Stephen, Lynch, and the three prostitutes enjoyed in the brothel. Since this dance immediately preceded the apparition of Stephen's mother as a ghoul commanding him to repent, the two interpretations are not totally unrelated. The morning's stereoscopic experience of seeing the sun from two slightly divergent perspectives continues here in interpreting Stephen's collapse in different (religious and scientific) but complementary ways.