Canadian Space Agency
The Astronautics Vocabulary is a glossary of terms that pertain to the science and technology of spaceflight. This alphabetical list can be navigated by clicking on the letters A-Z displayed on this page.
Definition: The atmospheric zone or shell located above the tropopause at an altitude of circa 20 to 50 km (circa 12 to 31 mi) and characterized by an increase in temperature with increasing altitude.
Other Definition: None