## 3 Proposed Model and Its Performance Evaluation  
To develop a unified empirical model for the prediction of global attenuation, real weather data from meteorological sites [23] have been collected for the metropolitan areas of New Delhi (India), Washington DC (USA), London (England), and Cape Town (South Africa) for the months of December 2022 to February 2023. The data set of 450 values comprised of daily meteorological records of visibility calculated for different weather conditions has been utilized for analysis. First, visibility data for each day has been collected for fog, haze, and cloud weather conditions, and the average value of visibility for three months has been calculated. Next, the average attenuation of each region has been analyzed as a result of different climatic conditions. The average visibility for three months and the corresponding attenuation calculated by employing [PERSON]'s model for New Delhi region is tabulated in Table 1.  
Figure 1 shows the plot of the average visibility for different months considering three weather conditions in the New Delhi region. The region has maximum and minimum visibilities of 5.25 km and 1.77 km in the months of January 2023 and December 2022 attributed to fog and cloud weather conditions, respectively. \begin{table}
\begin{tabular}{c c c c} \hline
**Weather Condition** & **Month** & **Visibility** & **Attenuation** \\ \hline Fog & December 2022 & 4.580 km & 1.252 dB/km \\ Fog & January 2023 & 5.258 km & 0.863 dB/km \\ Fog & February 2023 & 5.142 km & 1.982 dB/km \\ Haze & January 2023 & 2 km & 8.574 dB/km \\ Haze & February 2023 & 3.71 km & 3.481 dB/km \\ Clouds & December 2022 & 1.77 km & 10.065 dB/km \\ Clouds & January 2023 & 2.45 km & 6.496 dB/km \\ Clouds & February 2023 & 2.625 km & 5.890 dB/km \\ \hline \end{tabular}
\end{table} 
Table 1: Visibility and attenuation: New Delhi region. Figure 1: Visibility: New Delhi region. Table 2 depicts the average visibility and resultant attenuation for three months in the case of the Washington region. It records a minimum visibility and maximum attenuation of 13 km and 0.680 dB/km, respectively, in the month of February 2023 as a result of the fog weather condition. Figure 2 illustrates that an acceptable visibility and reduced attenuation is observed in the region in the case of cloud weather conditions. Table 3 and Figure 3 depict the observed visibility and average attenuation of the London region for the three months. It has been observed from Table 3 that the London region witnesses a minimum and maximum attenuation of 0.334 dB/km and 4.843 dB/km due to clouds and haze in the months of January 2023 and February 2023, respectively. Figure 4 and Table 4 present the values of visibility and attenuation for the three months in the case of the Cape Town region. The maximum and minimum visibility has been observed in the case of cloud and fog weather conditions with corresponding attenuations of 0.643 and 3.077 dB/km, respectively. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Weather Condition** & **Month** & **Visibility** & **Attenuation** \\ \hline Fog & December 2022 & 88.25 km & 0.073 db/km \\ Fog & January 2023 & 24.2 km & 0.365 db/km \\ Fog & February 2023 & 13 km & 0.680 db/km \\ Clouds & December 2022 & 243.38 km & 0.027 db/km \\ Clouds & January 2023 & 105.80 km & 0.061 db/km \\ Clouds & February 2023 & 20.56 km & 0.430 db/km \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Visibility and attenuation: Washington region. Figure 2: Visibility: Washington region. Figure 4: Visibility: Cape Town region. Figure 3: Visibility: London region.