"Rainbow Season" arrives with the first rains of the season. Scattered showers are best for rainbow watching: sunlight refracting and reflecting through the raindrops causes two bows to appear -- an intense circular arc at 42°, and a bigger, but weaker arc at 51° from the antisolar point (the point in the sky diametrically opposed to the sun's position). From November through mid-February, the sun never gets higher than 42° above the horizon as seen from San Diego, so (rain and sunlight permitting) the brighter of the two arcs may appear above the horizon at any time of day. In spring and summer, rainbows are never seen in the sky around midday because the sun is too high -- and the antisolar point is too low.
"Rainbow Season" arrives with the first rains of the season. Scattered showers are best for rainbow watching: sunlight refracting and reflecting through the raindrops causes two bows to appear -- an intense circular arc at 42°, and a bigger, but weaker arc at 51° from the antisolar point (the point in the sky diametrically opposed to the sun's position). From November through mid-February, the sun never gets higher than 42° above the horizon as seen from San Diego, so (rain and sunlight permitting) the brighter of the two arcs may appear above the horizon at any time of day. In spring and summer, rainbows are never seen in the sky around midday because the sun is too high -- and the antisolar point is too low.