Air Density (Deborah)
Air density is the mass per unit volume of Earthís Atmosphere.Air density decreases
with altitude, as does pressure. It also decreases with increasing temperature or
humidity. All particles in the atmosphere are drawn by the downward force of gravity.
Pressure in the air creates an upward force working opposite gravityís pull. Air density
builds to whatever level balances the force of gravity because at this point gravity
isnít strong enough to pull down a greater number of particles.