The investigation of tori in photographs was prompted by a chance photograph of an apparent optical effect taken outside of my home in the direction of a nearby airport. The photo showed a circular optical aberration of the scene centered on a lamp pole. Since the pole itself showed no evidence of distortion, the aberration seemed to be "out there" rather than something generated inside the camera. The nearest known photographic artifact would be lens flare. However, this requires a strong light source in the field of view, and this is not evident in the photo.
The following images show the phenomenon. On the left is the original photo, in the middle is the result of processing with the equalization tool, and on the right is the same image with circles drawn to direct attention to the optical aberration. Click on an image to view a larger version.
| Original | Processed | Marked |
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There seems to be no obvious explanation for the aberration. Since the airport lay in the direction of the shot, one might speculate that the visible effect was produced by an interaction of airport radar transmissions with the contents of the atmosphere. Thus began my examination to study the ubiquity of the phenomenon. A few more photos of the local sky showed a similar effect, but none were as striking as the initial photograph.