Brocken spectre and glory
2010-11-21 16:17:13.000 – Steve Welsh, IT Observer
After days of seeing nothing outside but freezing fog we were finally greeted to a wonderful sunrise soon followed by a great Brocken spectre and glory – one of the best I’ve seen up here. By the time I got outside with the camera it was wearing off but in the accompanying photo you can still make out the glory around the mountain’s shadow.
So a Brocken spectre is really just a shadow, in this case of the mountain peak, being cast on the clouds below. The shadow appears magnified due to an optical illusion caused by the way the shadow forms on the water droplets in the cloud. The magnification effect is formed since the cloud droplets, that reflect the image, are at varying distances from the observer plus there is a lack of any reference points in the cloud which also tends to confuse the eye.
The ‘rainbow’ or halo affect around the top of the shadow is an optical phenomenon called a glory. It is caused by light being backscattered (a combination of diffraction, reflection and refraction) towards the observer by the uniformly-sized water droplets in the cloud.
And now for something completely different – Mike washing up the dishes.
Steve Welsh, IT Observer