The strange picture under the flash

(Photo: mrshaw)

Try to imagine yourself standing in the middle of a thunderstorm in an old city. Under the flash you will see a strange scene. The bustling street seems to petrify for a moment: the horses are in the posture of pulling the car, legs are raised in the air; the vehicles also stood still, clearly seeing each spokes .

The reason for this apparent motion is because of the lightning, as well as all sparks, that exist for an extremely short period of time - so short that it cannot be measured by conventional means. But thanks to indirect methods, it was known that lightning existed from 0.001 to 0.2 seconds (lightning between clouds is longer, up to 1.5 seconds).

In such short periods of time, nothing moves clearly to our eyes. Each spokes of the wheel in the fast-moving vehicle could only move a very small fraction of a millimeter, and it was no different from the eyes. The impression is further enhanced because the image is saved in the eye longer than the lifetime of the lightning.