The stratosphere is a layer of Earth's atmosphere that begins about six miles above the surface and extends up to about 30 miles high. If you could ride an elevator straight up from the ground, you'd pass through the troposphere (where weather happens and planes fly), then enter the stratosphere, where the air becomes incredibly thin and cold.

The stratosphere contains the ozone layer, which protects Earth by absorbing harmful ultraviolet radiation from the sun. This absorption actually warms the stratosphere, making it unusual: unlike the troposphere below it, the stratosphere gets warmer as you go higher, not colder.

Very few things reach the stratosphere. Weather balloons carry scientific instruments there to study atmospheric conditions. Some specialized aircraft can fly at its lowest levels. When volcanoes erupt violently, they sometimes shoot ash and gases into the stratosphere, where those particles can spread around the entire planet and affect climate for years.

People often use “stratospheric” to describe something that has risen to extreme heights: stratospheric prices means costs have shot up dramatically, while stratospheric success means achievement that towers far above the ordinary. The word captures that sense of reaching levels most things never approach.