Earlier this month, on a
nice day, Felix Baumgartner jumped from
39,045 meters, or 24.26 miles, above the Earth from a capsule lifted by a
334-foot-tall helium filled balloon (twice the height of Nelson's column and 2.5 times the diameter of the Hindenberg). Wolfram|Alpha tells us the jump was equivalent to a fall from 4.4
Mount Everests stacked on top of each other, or falling 93% of the length of a marathon.
At
24.26 miles above the Earth, the atmosphere is very thin and cold, only about
-14 degrees Fahrenheit on average. The temperature, unlike air pressure, does not change linearly with altitude at such heights. As Wolfram|Alpha shows us, it rises and falls depending on factors such as the decreased density of air with rising altitude, but also the absorption of UV light by the ozone layer.
At 39 kilometers, the horizon is roughly 439 miles away. At this layer of the atmosphere, called the
stratosphere, the air pressure is only
3.3 millibars, equivalent to 0.33% of the air pressure at sea level. To put it another way, the
mass of the air above 39 kilometers is only 0.32851% of the total air mass. Given this knowledge, we know that 99.67% of the world's atmosphere lay beneath him. This information was important to Felix's goal to break the sound barrier in free fall because the rate of drag is directly related to air pressure. With less air around him, there would be less drag, and thus he could reach a higher maximum speed. Of course, this would require him to wear an oxygenated suit to allow him to breathe, in addition to keeping him warm.