Visibility forecast in the phase of pre-condensation

Abstract

The effect on visibility of the swelling of aerosol particles due to increasing humidity is studied. The swelling can be described by r(f)/r(0) = (1 - f)=1/μ where r(f) = particle radius at relative humidity f and μ = const μ 4 on the average. The visibility variation is expressed as V(f)/V(f0) = [(1 - f)/(1 - f0)]V* μ 1)/μ where V* = exponent of the aerosol size distribution μ 3 on the average. The last formula allows to compute the standard visual range V(f) at relative humidity f from the present standard visual range V(f0) at present relative humidity f0.