Cirrus clouds, those high, wispy-looking clouds you see on a clear day, are above 18,000 feetabout 3.5 miles high.
The highest clouds ever recorded were just under 60,000 feet, or about 11 miles high, though the instruments used to measure such things are less than precise.
To put this in perspective, Mount Everest is 29,035 feet (5.5 miles) high, and the Boeing 747 is allowed by law to fly as high as 45,100 feet, or a little over 8.5 miles high.
We think that’s pretty high. Now we know it’s just that much more difficult to “fly high above the clouds”. Whoever came up with that phrase probably didn’t know what they were talking about.