Answer · confidence: partial
How do ground-based instruments measure how much aerosols scatter light at different humidity levels in clean summer air?
The records show that the general dependence of aerosol scattering coefficients on relative humidity is expressed by the formula σ∼λ−γ(1 −H)R 1. These empirical coefficients are related to aerosol microstructure and to each other by a simple relationship 2. In the southeastern US, the relationship between aerosol optical depth and dry aerosol mass is specifically sensitive to relative humidity 4. The provided facts describe analytical models and regional sensitivity but do not detail the specific operational procedures of ground-based instruments for measuring these values in clean summer air.
Checked 2026-10-16. Only documented and supported facts are used.
Dig deeper on this questionSources
[1] documented
The general dependence of aerosol scattering and absorption coefficients on wavelength and relative humidity can be expressed by the formula σ∼λ−γ(1 −H)R.
"It is shown that the general dependence of the aerosol scattering and absorption coefficients on λ andHcan be presented in the form σ∼λ−γ(1 −H)R."A simple analytical model of aerosol properties with account for hygroscopic growth: 2. Scattering and absorption coefficients (1999)
[2] documented
The empirical coefficients of the Angstrom wavelength law and the Kasten-Hane humidity law are related to aerosol microstructure and to each other by a simple relationship.
"The empirical coefficients of these laws are related to the aerosol microstructure and to each other by a very simple relationship."A simple analytical model of aerosol properties with account for hygroscopic growth: 2. Scattering and absorption coefficients (1999)
[3] documented
At very high humidities, a dense haze with visibility less than 1 km can form under subsaturated conditions without the presence of activated droplets.
"It is shown that at very high humidities a dense haze with visibility less than 1 km may form under subsaturated conditions and without activated droplets."A simple analytical model of aerosol properties with account for hygroscopic growth: 2. Scattering and absorption coefficients (1999)
[4] documented
The relationship between AOD and dry aerosol mass in the southeastern US is highly variable and specifically sensitive to relative humidity (RH).
"These observation- ally based sensitivity studies indicate that the relationship between AOD and dry aerosol mass in these conditions in thesoutheasternUScanbehighlyvariableandisespecially sensitivetorelativehumidity(RH)."Aerosol optical properties in the southeastern United States in summer – Part 2: Sensitivity of aerosol optical depth to relative humidity and aerosol parameters (2016)