Rainbow Visible after Sunset

Abstract

IT may be of interest to record that about sunset on Monday, June 4, there was a fine rainbow here which persisted until the sun was well below the horizon. The last trace of it vanished at 20^h 11^m G.M.T., at which time the altitude of the true sun was approximately minus 1° 30prime;. Making a generous allowance for refraction, this would still put the upper limb of the apparent sun very appreciably below the horizon. This is perhaps the more remarkable in that there was a low bank of cloud along the western horizon. The great altitude of the top of the bow was very striking, and it did not, of course, reach down to ground level, but faded out at a considerable height, which there was not time to measure. My longitude and latitude were 4^m 28^s E., 51° 21′ N.