Introduction of activity, and model of confined-activity for temperature (§2.2)
The temperature of the ambient air is consequential to the Maxwellian motion of the air molecules introduced in section §2.1 and illustrated in figure 2.2.1 on your left. Bring the mouse pointer over the images to make the molecules move.
Animated molecules
Animated molecules
The faster the molecules the hotter the air.
And in accordance with gravimotion's interpretation of motion
Subject §1.1 recollection:
Motion occurs, and motion is self-sufficient
Here is Newton’s first law traditionally called the inertia law:
Any object at rest or in uniform motion remains at rest or in uniform motion as long as no force is applied.

By tradition it is the object's inertia that maintains its uniform motion; yet inertia, which cannot be measured, and which has never been assigned a unit of measure, is not a physical entity.
Inertia which is fictitious is simply not the cause of uniform motion.

Unless one denies its occurrence, uniform motion is compelled to occur by itself.
In the real world uniform motion occurs and is self-sufficient!
, the individual motions of the molecules are separate entities from the molecules matter.
Animated molecules
Animated molecules
As such these motions can be represented independently of the molecules that is without representing the molecules' matter and with motion-occurrences as done in figure 2.2.2 on the right.
The motion-occurrences of the figure 2.2.2, which represent the motion of the air molecules, are constantly wiggling around, constantly colliding and rebounding in between themselves, yet having specific thrust.
In favor of such an independent representation of the motions of the molecules (not showing the molecules) is the fact that these very motions are themselves transferable from a bunch of molecules to another bunch under the form of heat (transfer of temperature).
Note there is no forces involved; the motion of the molecules just happens (coincidental to physics' concept of energy)!
In gravimotion the motion of the molecules is borrowed from the present mo(ve)ment (intoduced §1.13); the motion of the molecules happens as combinations of motion-quanta. Subsequent subjects of this treatise explain how that happens.
The Maxwellian motion of air molecules on earth is furthermore and specifically given the name confined-activity in gravimotion. As an example the air molecules we breathe is confined by gravity to a volume surrounding Earth.

Even though that is not the dictionary definition, the word activity is used when crowds of individual motion occurrences are acting in concert.
In gravimotion an activity coincides to the behavior of a great number of motion-occurrences having a common behavior.
An activity occurs exclusively as motion, matter being excluded.
Confined-activity is a crowd of MOs that have a common characteristic that of Maxwellian motion.
Yet now instead of speaking of temperature, which is a single number such as 700 Fahrenheit, and as such is an abstracttion of reality, we speak of the fundamental phenomenon, which is activity or a complex situation involving motion.