Consider an idealized cloud consisting of spherical droplets with a uniform radi
ID: 160016 • Letter: C
Question
Consider an idealized cloud consisting of spherical droplets with a uniform radius of 10 µm and number concentration of 300 droplets/cm3 . How far into this cloud would the light need to travel to be depleted by a factor of e (1/2.7 = 36.8% its original intensity)? In other words, what is the e-folding depth of light passing through such a cloud. (Assume that none of the scattered radiation is subsequently scattered back into the path of the beam, and none is absorbed.) [Hint: Realize that because the cloud droplets are so much larger than the wavelengths of visible light that they scatter according to their geometrical cross section, and then apply Beer's law.]
Explanation / Answer
Consider an idealized cloud consisting of spherical droplets with a uniform radi