A&O 2 - Lecture 7

A&O 2 - Lecture 7 - Aerosols Peaks in size...

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1 Aerosols • Size distributions • Sources and composition • Growth processes • Health effects • Remediation (removal processes) 2 Size Distributions 10 5 – 10 7 0.001 – 0.01 1000 – 8000 Raindrops 10 5 – 10 7 0.01 – 1 200 – 1000 Drizzle 10 4 – 10 7 1 – 1000 10 – 200 Cloud droplets 10 4 – 10 6 1 – 500 10 – 20 Fog droplets Hydrometeors < 250 < 1 – 10 > 2.0 Large < 250 1 – 10 4 0.2 – 2.0 Medium < 1 10 3 – 10 6 < 0.2 Smal Aerosol particles 1.2 x 10 9 2.45 x 10 19 0.0005 Gas molecules Diam., μm No./cm 3 Mass concen., μg/cm 3 3 0.1 μm 2.0 μm Peaks in size distribution are called modes Nucleation mode Accumulation mode Coarse mode 4 • Nucleation Mode: newly emitted or nucleated particles are smallest (< 0.1 μm) ! Most numerous of particles, but not much total mass burden • Accumulation Mode: two modes from growth of particles by coagulation or condensation (0.1 – 2 μm) ! Long lifetimes (days, weeks) ! Deeply penetrates into lungs ! Affects visibility
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This note was uploaded on 10/04/2009 for the course A&O A&O 2 taught by Professor Lew during the Spring '09 term at UCLA.

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A&amp;O 2 - Lecture 7 - Aerosols Peaks in size...

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