GEOG 101 Lecture Notes - Lecture 6: Pressure Altitude, Atmospheric Circulation, Density
28 Sep 2018
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Document Summary
Relationship between temperature, volume, pressure, and density of a gas. Pressure changes if the volume changes (p) Pressure changes if the density changes (p) P = r p t: r is constant. Pressure is a force exterted on an area from all directions. In gas it is related to collision of molecules. Compress gas into a smaller volume = more collisions/area. If gas cools, molecules are less energetic, so fewer collisions and lower pressure. Variation: decreases with altitude, decreases as temperature increases. Inches of mercury (hg: millibars (mb, standard atm. Pressure: =sea level pressure, 1 atm = 1013. 25 mb, = 15 psi. New insturments: radiosondes (balloons, launched twice a day at key locations in us, dropsondes (parachuted, 1000 per year dropped by hurricane hunter aircraft, *both measure, pressure, altitude, gps location, temperature, relative humidity, wind speed and direction. Thermosphere: warmer but very few molecules and very low pressure, site of aurora.
