<Li> 99.99997% is below 100 km (62 mi; 330,000 ft), the Kármán line . By international convention, this marks the beginning of space where human travelers are considered astronauts . </Li> <P> By comparison, the summit of Mt . Everest is at 8,848 m (29,029 ft); commercial airliners typically cruise between 10 and 13 km (33,000 and 43,000 ft) where the thinner air improves fuel economy; weather balloons reach 30.4 km (100,000 ft) and above; and the highest X-15 flight in 1963 reached 108.0 km (354,300 ft). </P> <P> Even above the Kármán line, significant atmospheric effects such as auroras still occur . Meteors begin to glow in this region, though the larger ones may not burn up until they penetrate more deeply . The various layers of Earth's ionosphere, important to HF radio propagation, begin below 100 km and extend beyond 500 km . By comparison, the International Space Station and Space Shuttle typically orbit at 350--400 km, within the F - layer of the ionosphere where they encounter enough atmospheric drag to require reboosts every few months . Depending on solar activity, satellites can experience noticeable atmospheric drag at altitudes as high as 700--800 km . </P> <P> The division of the atmosphere into layers mostly by reference to temperature is discussed above . Temperature decreases with altitude starting at sea level, but variations in this trend begin above 11 km, where the temperature stabilizes through a large vertical distance through the rest of the troposphere . In the stratosphere, starting above about 20 km, the temperature increases with height, due to heating within the ozone layer caused by capture of significant ultraviolet radiation from the Sun by the dioxygen and ozone gas in this region . Still another region of increasing temperature with altitude occurs at very high altitudes, in the aptly - named thermosphere above 90 km . </P>

What are all the layers of the atmosphere