A Brocken spectre (Brockengespenst) makes an appearance on the way to the summit of Mangerton mountain in Co. Kerry on the October Bank Holiday weekend.
Wikipedia has a good explanation of a Brocken spectre – basically, it is your shadow cast large on a cloud surrounded by a ‘rainbow’. It can be seen at its best when walking along ridges with the sun on one side and a fog or cloud canvas on the other, typically below. As we walked along the edge of a steep drop towards the top of Mangerton mountain in Kerry, the sun flickered briefly through the cloud, projecting our shadows on the cloud below, along with rainbow rings around them. Though cloud swirled around the top of the mountain, it was clear and sunny everywhere else. That’s Lough Leane and the town of Killarney in the background.