Swan Lake Electrical Fog

Strange Electrical Fog in Yellowstone Park

What exactly was the electrical fog that engulfed William B. Sanborn in Yellowstone National Park in September of 1949?

In a report logged in Natural History V.59 of 1950 is the strange account of an experience with a strange blue electrical cloud flowing across the ground in Yellowstone National Park. While this was likely a natural phenomenon, it highlights that strange things happen that we still can’t fully explain.

Swan Lake in Yellowstone, where a strange blue electric cloud was seen.
Swan Lake where Sanborn saw his strange electrical phenomenon.

To set the stage, Mr. Sanborn was driving from Madison Junction to Mammoth Hot Springs in the Yellowstone Park in early September of 1949. An electrical storm was raging in the mountains around him and he even notes in his report that the nearby Electric Peak “derives its name from the electric storms that frequent its heights and the surrounding region.”

As he drove onto a long straight stretch along the shore of Swan Lake, he noticed something strange. There was a bluish light coming from a ridge to the west of Swan Lake. At first he thought that it might be a fire sparked by the lightning, but then was startled to see the blue light moving up and over the ridge in his direction.

The patch of light came over the ridge, down its slope and out over the marsh and lake. This electrical fog was his estimation ~150′ across and 750′ in length. Over the blue electrical pool, he could see a “very low lead-gray cloud”. Crossing the swamp it startled some waterfowl causing them to fly away. He continued watching the fog until it finally moved up to and engulfed him and his car.

To describe the weird feeling caused by viewing the progress of this phenomenon is difficult. It kept low to the ground, actually “flowing around” everything that it came in contact with, coating it with a strange pulsating light. Each twig on the sagebrush was surrounded by a halo of light about two inches in diameter. It covered the automobile and my person but did not cover my skin. There was a marked tingfing sensation in my scalp, and brushing my hair with the hand caused a snapping of tiny sparks.


The electrical charge acted almost like water, flowing around objects and could even be brushed off of his car, though it quickly filled back in. Interestingly enough, he noted that when he threw a rock that the fog would dissipate where the stone hit, only to fill back in.

Every time the rock hit the ground or a piece of brush it gave the appearance of “splashing.” The light would momentarily disappear from the contact spot but immediately build up again.

He continued watching the electrical fog move up the valley towards Electric Peak until it was out of sight. While standing in the cloud he felt no ill effects, but when he got in his car and touched a metal surface (cars had those back then) he got a sizable shock that left his arm numb for several hours.

In researching the event he talked to Ross Gunn, Director of Physical Research at the United States Weather Bureau who explained that it was a byproduct of the electrical storm high above and that “Usually the described effects are short-lived and precede a lightning discharge. The glow results from ionization induced by a highly electrified cloud overhead”. If this is the case, Mr. Sanborn sound quite lucky to have left the experience with just a jolt to the arm.

Have you seen anything like this?

This phenomenon reminds me of the numerous occurrences of ball lightning that seems to appear from nowhere, sometimes entering homes through walls or closed windows. Evidently, the rules what we know don’t always apply to electrical charges.

Have you experienced any strange electrical phenomenon? Leave a comment or send us some mail and let us know. We would love to hear about it.

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