micro- scale urban or regional or synoptic or local scale mesoscale global scale 100y long-lived species CFC's N20 CHA 10yr inter-hemispheric mixing time 1yr RESIDENCE TIME CH3CCI CH3 Br moderately long -CO lived species -Aerosols Trop og -HO SO2 H2O2 -NOX intra-hemispheric mixing time - boundary layer mixing time 1 day DMS -CH6 CsHg 1hr short-lived 100s species .CH3O2 HO2 NO3 1s OH 1m 10m 100m 1km 10km 100km 1000km 10.000km SPATIAL SCALE OF VARIABILITY Chemical Engineering Homework Problem: Ammonia (NH3), nitrous oxide (N20) and methane (CH4) comprise 1 x 10-8, 3 x 10-5, and 7 x 10-5 % by mass of the Earth's atmosphere, respectively. If the effluxes of these chemicals from the atmosphere are 5 x 10^10, 1 x 10^10, and 4 x 10^11 kg a-1, respectively, what are the residence times of NH3, N20, and CH4 in the atmosphere? (Mass of the Earth's atmosphere = 5 x 10^18kg.) =