#656 A Rainbow Shiur
Is there a minimum shiur of rainbow that has to be seen in order to make the beracha or is any small amount enough (in length or in number of colors)?
Poskim disagree; Biur Halocho (229: 1) queries whether in order to recite a brocho on a rainbow one needs to see the full semicircle or even part of it is enough. Teshuvos Vehanhogos (O.H. 3: 76) rules that since Biur Halocho remains uncertain, as in every Sofek brocho (doubtful blessing) no brocho should be recited. Vezos Habrocho (p. 156) maintains that if only a small part is missing, a brocho can be recited.
However, other Poskim aver that even part of the rainbow is after all enough to bring to memory the established covenant and therefore suffices for a blessing (Chazon Ovadia p.473 quoting various other Poskim, Yalkut Yosef 3: 229:1, P’ninei Halocho p.227, Nesivei Halocho 229: 1)
Horav Shlomo Miller’s Shlit"a opinion is that if it shows the curvature of an arc, and as long as most people recognize it as a rainbow and call it so, one can recite a brocho over it.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit"a
Answered by: Hagaon Rav Shlomo Miller Shlit'a
Published: November 21, 2014