Mixing ratio is the ratio of two components of a gas,
a term used in the study of atmospheres, such as
meteorology. In some fields, the convention is to
state the ratio by mass whereas in others, the convention
is to state the ratio by mole (molecular count). A common
use is to describe the amount of water vapor in an atmosphere.
For example, the ammonia and water vapor mixing ratios
of Jupiter's atmosphere are of interest.