Question

2 1. Scattering cross-section of acrosol particles is 2.5E-12 m , absorption cross-section is 0.45E- .2 12 m Concentration of particles is N 2E7 1/m. Calculate the optical thickness and transmittance of atmosphere at this wavelength if sun zenith angle is 40 degrees and the thickness of aerosol layer is 2.5 km.

Answer 1

Answer:

$T = 3.23 \times 10^{-83}$

Explanation:

thickness of aerosol layer is 2.5 km

zenith angle is 40 degree

we know that

$\tau = \epsilon_{ext} . h$

where

$\epsilon_{ext} = N.\sigma_{ext}$

$\epsilon_{ext}$ is extinction coefficient

$\sigma_{ext}$ extiction cross section

N = Concentration

$\sigma_{ext} = (2.5 + 0.45)\times 10^{-12} m^2$

                     $= 2.95 \times 10^{-12} m^2$

$\epsilon_{ext} = 2\times 10^7 \times 2.95 \times 10^{-12} m^2 \times m^{-3}$

                       $= 5.9 \times 10^{-5} m^{1}$

$\tau = 5.9 \times 10^{-5} m^{-1} \times 2.5\times 10^3 m$

        $= 14.75\times 10^{-2}$

transimiitance $T = e^{\frac{-\tau}{\mu}}$

                       $T = e^{\frac{- 14.75 \times 10^{-2}}{cos 40}}$

$T = 3.23 \times 10^{-83}$