GG101 Lecture Notes - Lecture 3: Chlorofluorocarbon, Radiography, Noctilucent Cloud
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4less: odorless, colorless, tasteless and formless = air. Atmosphere thickness is about 480km (thermopause), beyond that altitude is the exosphere (outer sphere) Density = mass/volume, air density = 1. 2kg/m-3, liquid water density = Elevation = height above point on earth, can stand on it. Altitude = something above the surface, cannot stand on it. Exosphere (cid:498)outer sphere(cid:499), where the rarefied, less dense atmosphere is nearly a vacuum, contains scarce lightweight, hydrogen and helium atoms, weakly bound by gravity as far as 32,000km from the earth. Air pressure changes throughout the atmospheric profile, air molecules create air pressure through their motion, size and number, exerting force on all surfaces that they come in contact with. This same pressure also exists inside us otherwise we would be crushed by the mass of air around us. The atmosphere exerts an average force of approximately 1kg/cm-1 at sea level; with increasing altitude, density and pressure decrease.
