ATMOSPHERIC CHEMICAL SYSTEMS October 1992 Source: NAsa
ATMOSPHERIC CHEMICAL SYSTEMS Source: NASA
IMPORTANCE OF ATMOSPHERIC CHEMISTRY Climate Change Stratospheric ozone ATMOSPHERIC CHEMISTRY Regional air pollution Acid Deposition
ATMOSPHERIC CHEMISTRY Climate Change Regional Air Pollution Acid Deposition Stratospheric Ozone IMPORTANCE OF ATMOSPHERIC CHEMISTRY
ATMOSPHERE STRUCTURE BULK COMPOSITIon Atmospheric pressure(millibars-mb 02004006008001000 120 80 Temperature Pressur 100 Thermosphere Pressure units Mesopause 1atm=1013×106gcms2 Mesosphere 1 mbar 103 g cm-Is-2 g60 40a Stratopause 1 hPa= 10 g cm-ls2 40 Stratosphere. Ideal gas law Tropopause 20 (p R T)/Ma Troposphere 4048012 Temperature(°c) Source: Environmental Science, Cunningham, P. W and B. W Saigo, 200/
ATMOSPHERE STRUCTURE & BULK COMPOSITION • Pressure units 1 atm = 1.013 x 106 g cm-1 s -2 1 mbar = 103 g cm-1 s -2 1 hPa = 103 g cm-1 s -2 • Ideal gas law p V = Rg T p = ( Rg T)/Ma Source: Environmental Science, Cunningham, P. W. and B. W. Saigo, 2001
ATMOSPHERIC TRANSPORT TIME SCALES 2 weeks 1-2 months Equate stratopause tropopause ..--... 5-10yr mo PBL top wk (1-3 km)1-2 days surface Source: Introduction to Atmospheric Chemistry, Jacob, D.J., 1999
ATMOSPHERIC TRANSPORT TIME SCALES Source: Introduction to Atmospheric Chemistry, Jacob, D. J., 1999
TYPICAL ATMOSPHERIC COMPOSITION (mole fraction) ypical units 0.78 Number concentration molecules cm-3 02 0.21 Mixing ratio: ppm, ppb, ppt Ar 0.093 <0.0001-0.04. Molecular weight of air CO2 370 ppm Ma=28.96 g mole-I CH4 ppI 10 ppb-10 ppm Trace chemistry co 50 ppb-300 ppb Reactants are present in trace amounts NO ppb-1 ppt OH pp
TYPICAL ATMOSPHERIC COMPOSITION N2 0.78 O2 0.21 Ar 0.093 H2O <0.0001-0.04 CO2 370 ppm CH4 1.7 ppm O3 10 ppb – 10 ppm CO 50 ppb – 300 ppb NOx 5 ppb – 1 ppt OH < 1 ppt (mole fraction) • Typical units Number concentration: molecules cm-3 Mixing ratio: ppm, ppb, ppt • Molecular weight of air Ma = 28.96 g mole-1 • Trace chemistry Reactants are present in trace amounts