Britannica
Sources used in this answer
How does the homosphere differ from the heterosphere?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
Atmosphere
The atmospheres of planets in the solar system are composed of various gases, particulates, and liquids. They are also dynamic places that redistribute heat and other forms of energy. On Earth, the atmosphere provides critical ingredients for living things. Here, feathery cirrus clouds drift across the deep blue sky over Pinawa Dam Provincial Park, near Pinawa, Manitoba, Canada.
The Earth's atmosphere is divided into two primary zones based on how gases are distributed: the homosphere and the heterosphere.1
Key Differences
- Composition and Mixing: In the homosphere, which extends from the surface to approximately 100 km, turbulent mixing dominates. This process ensures that the chemical composition of the atmosphere remains relatively uniform and independent of height. In contrast, the heterosphere—located above 100 km—is characterized by molecular diffusion. In this region, gases are separated according to their molecular mass, causing lighter gases to concentrate in the highest layers.1
- Vertical Distribution: Because of these differing physical processes, heavier gases like nitrogen decrease rapidly with height in the heterosphere, while lighter elements such as helium and hydrogen become the dominant species at altitudes above 1,000 km.1
- Transition Zone: The boundary between these two regions, located at about 100 km, is known as the turbopause.1