One man is known to have fallen from cloud nine and survived.
Cumulonimbus incus, referred to as cloud nine by cloudspotters, can reach heights of 65,000 feet only stopping in growth at the borders of the troposphere and stratosphere, where its anvil of ice crystals spreads out, feeding negative charged ice crystals into the storm inside. All airplanes fly over or around these clouds as passing through could destroy them.
In the late 60s, Lt. Cl. William Rankin was on a routine flight in an F8U-209 Crusader jet and at around 47 thousand feet passing over a cumulonimbus cloud when his engine lost power. He pulled the lever to transfer auxiliary power, but that broke off in his hand. He had to eject.
As he free fell into the thundercloud, although he was able to put on his oxygen mask, his body expanded in decompression, and all exposed skin began to frostbite, numbing him from the sharp pain he initially felt. Battered by large hailstones, after ten minutes of falling, when he thought he was at 10,000 feet his parachute opened. Then his real troubles began.
Winds kept him in the cloud for another half hour, pulling him up and down as far as 6000 feet, twirling him around until he vomited, thrusting him through thick rain that he had to hold his breath to keep from drowning, lifting him up into his chute or looping around it. The hundreds of thousands of hailstones were picking up electrons from hitting ice crystals, building up the charge that causes lightning, which Rankin experienced as seeing huge blue blades several feet thick. The extreme heat of lightning (27,000 degrees C) explodes the air around it in millionths of a second, resulting in thunder.
"I didn't just hear the thunder,' Rankin later wrote, 'I felt it."
Convinced of his death, the afterimage of a fork behind his chute gave him the vision of a glowing cathedral, and as this burned away, he found he was in less turbulence and thinner rain, and was soon tangled into a tree in a Carolina pine forest. With no broken limbs, he orientated himself to a road, and was picked up and taken to hospital: heavily bruised, covered in frostbite, with the impressions of his flight jacket's stitches over his body from expanding 10 miles up on cloud nine, and hoping to be back in the skies by the next month.
He died at the age of 89 in 2009.
(this was inspired by reading about it in The Cloudspotter's Guide. Rankin wrote a book a year after his experience, now out of print, called 'The Man Who Rode the Thunder'; every single review online of the book is enthusiastic. In 1975, skydiver Mike Mount was also sucked into a cumulonimbus at a height of 4500 feet and had a similar experience inside.)