Tracer, trace gas, trace constituent:
Minor ingredients of the air - except water (vapor) and ice.

The lower most "floor" of the atmosphere, located between ground surface and ~12km at the poles and ~16km in the tropical belt respectively. The troposphere is separated from the stratosphere by the tropopause basically marked by a local minimum in the vertical temperature profile.

The genaral circulation::
Large scale air motion driven by sun radiation heating in the tropics and diverted by the corriolis force (more detaled explanation follows).

Turbulent diffusion:, eddy diffusion:
Small scale air motion driven by e.g surface roughness (more detaled explanation follows).

Lifetime (chemical / radioactive):
The global atmospheric lifetime (yr) characterises the time required to turn over the global atmospheric burden. It is defined as the burden (mass) divided by the mean global sink (mass/yr) for an atmospheric partial constituent in steady state (i.e., with unchanging burden).

Amount of melecules of a species released into the air (molecules cm-2 s-1)

Loss = Loss rate (s-1) ("sink, depletion")

C = concentration converted to molecules cm-2

Mixing ratio is defined as the fraction of tracer molecules to total air molecules.

Interhemispheric exchange: North/south cross equatorial transport.

ITCZIntertropical Convergence Zone: Near equatorial belt of strongest updrought caused by solar radiation, following the zenit location of the sun.