The Collaborative International Dictionary
Aerostatics \A`["e]r*o*stat"ics\, n. The science that treats of the equilibrium of elastic fluids, or that of bodies sustained in them. Hence it includes a["e]ronautics.
Wiktionary
n. (context physics English) the study of gases in equilibrium and of balloons or aircraft in varying atmospheric conditions
Wikipedia
A subfield of fluid statics, Aerostatics is the study of gases that are not in motion with respect to the coordinate system in which they are considered. The corresponding study of gases in motion is called aerodynamics.
Aerostatics studies density allocation, especially in air. One of the applications of this is the barometric formula.
An aerostat is a lighter than air craft, such as an airship or balloon, which uses the principles of aerostatics to float.
Usage examples of "aerostatics".
Now I shall have to write a report in qui-quintuplicate to the Aerostatics Guild.