Experimentally determined relationship between extinction coefficients and liquid water content.

Area of Science:

• Atmospheric Science
• Optical Physics

Background:

• Fog significantly impacts visibility and climate.
• Accurate measurement of fog optical properties is crucial for modeling and prediction.
• Previous studies have explored the relationship between extinction and liquid water content, but experimental validation across various fog types is ongoing.

Purpose of the Study:

• To experimentally determine the relationship between extinction coefficients and liquid water content in fogs.
• To investigate the influence of droplet size distribution on this relationship.
• To measure the spectral variation of extinction coefficients within the infrared spectrum.

Main Methods:

• Simultaneous environmental chamber measurements of extinction coefficients at 10.27 micrometers and liquid water content.
• Inclusion of droplet size distributions ranging from light to heavy fogs.
• Measurement of spectral variation of extinction coefficients between 9.2 and 10.8 micrometers.

Main Results:

• A linear relationship was observed between extinction coefficients and liquid water content.
• This relationship showed minimal dependence on droplet size distribution.
• Measurements were consistent with theoretical calculations and predictions.
• Spectral variation of extinction coefficients agreed well with calculated values for typical fog droplet sizes.

Conclusions:

• The study confirms a robust linear relationship between fog extinction and liquid water content.
• Droplet size distribution has a limited impact on this fundamental optical property.
• Experimental data supports theoretical models, enhancing the understanding of infrared radiation interaction with fog.