Atmospheric aerosols L7-8 Flashcards
How do we calculate the scattering optical cross-section
The scattering optical cross section is calculated from the ratio of the scattered intensity and the incident irradience
Csca = Wsca/Ii
What is the equation to calculate cross section for absorption
Cabs = Wabs/Ii
Cabs - cross section for absorption
Wabs - ratio of absorbed intensity
Ii - incident irradience
What is the equation to calculate cross section for extinction
Cext = Wext/Ii
Cext - cross section for extinction
Wext - ratio of extinction intensity
Ii- incident irradience
Total extinction in the sum of scattering and absorption
Cext = Cabs + Csca
What is the optical cross section
The optical cross-section can be thought of as the cross-sections of the shadow cast by the object when illuminated
How to calculate extinction efficiency
Qext = Cext/σgeom
σGeom - the geometric cross section
How to calculate scattering efficiency
Qsca = Csca/σgeom
How to calculate absorption efficiency
Qabs = Cabs/σgeom
What is an extinction paradox
The particle is able to absorb/scatter more light than is geometrically incident upon it
How are rainbows formed
A rainbow forms when light is refracted, reflected, and dispersed inside water droplets. The different wavelengths of light are bent by different amounts, leading to the formation of a spectrum of colors. The rainbow appears at an angle of approximately 42° relative to the direction of the sunlight, with red on top and violet at the bottom.
When is the radius of the rainbow less
radius of rainbow is less with salt water aerosols
When double rainbows arise
Double rainbows arise from two reflections in the droplets
what happens during phase inversion in pressurised aerosol containers
rapid pressure drop causes bubble bursting and liquid dropley formation e.g in spray cans
how does hygroscopic growth affect aerosols in the respiratory tract
particles absorb water, increasing i size and altering deposition patterns
what determines the residual particle size in aerosol delivery
initial loss of volatiles through evaporation
