|A majestically frontlit cone tornado pulls tons of red Kansas dirt into its debris cloud as it passes very close to the town of Attica, Kansas on May 12, 2004. Notice the 'clear slot', the bright area cutting into the cloud base just behind the funnel. This marks the presence of the 'RFD', or rear flank downdraft, wrapping around the mesocyclone. The formation of a RFD and its associated 'clear slot' often precede the formation of a tornado. Also note the large hailstones on the ground, which were falling when this image was taken. Image from 35mm slide.
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