## 4 Conclusions  
The thermal and radiative properties of the urban atmosphere and surfaces properties collected in summertime of 2018, allowed us to have an integrative view of the processes and patterns characteristics in two urban canyons in the neighborhood of Telheiras (northern Lisbon district). The results showed that all surfaces respond directly to the amount of incident radiation. It was observed that, in the morning, the east facade presented higher radiation balance values than the west facade, reaching its maximum at 1 p.m., in the summertime, with a maximum of 825.4 W\(\cdot\)m\({}^{-2}\). During the afternoon, the highest values were recorded on the west facade, with a maximum of \(\sim\)722 W\(\cdot\)m\({}^{-2}\), at 3 p.m., in the summer. In the facades exposed to the north and south, the radiative performance was as follows: at the time of maximum sun elevation, the south facade presented a higher radiation balance than the north facade, with values of \(\sim\)632 W\(\cdot\)m\({}^{-2}\) versus \(\sim\)559 W\(\cdot\)m\({}^{-2}\) (in the north facade). Regarding the temperature of the different surfaces of the urban canyon, the south facade always presented higher temperatures when compared to the north facade, with the greatest differences observed at 3 p.m. The facade exposed to the east only presented higher temperatures at 1 p.m. In the morning and in the afternoon, the west facade always presented higher values, on average (+2.3\({}^{\circ}\)C) in summertime. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Time**} & \multicolumn{3}{c}{**Materials**} \\ \cline{2-4}  & **Asphalt** & **Sidewalk** & **Pavement** \\ \hline
9 a.m. & 136.2 & 105.9 & 69.1 \\
1 p.m. & 873.9 & 724.8 & 888.0 \\
7 p.m. & 191.9 & 125.9 & 136.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Q * of different materials used on horizontal surfaces of the study area (W\(\cdot\)m\({}^{-2}\)). About the radiation condition of the three types of floor (flat surfaces), asphalt showed the highest values when compared to the pavement of the Portuguese light-colored sidewalk. As for the radiation balance, asphalt presented the highest temperatures, when compared to the Portuguese sidewalk (+4.9 \({}^{\circ}\)C). When compared to the pavement, asphalt always presented higher temperatures, on average (+12.9 \({}^{\circ}\)C), during the day. With this work, it was confirmed that the use of a microclimatic network to monitor the air temperature is fundamental at the micro-meteorological scale. The results obtained during the period between April and July in the studied urban canyon allowed us to conclude that air temperature is higher in the east/west oriented street than in the north/south canyon. These differences, which never exceed 1.2 \({}^{\circ}\)C, were more evident in the afternoon, between 3:00 p.m. and 8:00 p.m. The few differences in thermal responses of the different urban materials, both on facades and surfaces, are related to the fact that the types of materials used in urban areas are not very diversified. Roads are usually built using asphalt or concrete, which have high absorption and low reflective capacities. This causes a major accumulation of energy on these surfaces, which is later released into the atmosphere, contributing to warming up the urban canopy layer [23; 24]. In the case of materials and colors used in the facades, we can conclude that due to the multiple reflections that occur in urban canyons, it is easier for these materials to absorb energy, releasing it to the atmosphere, especially at night time when the radiative balance is negative. In future investigations, it would be important to include other urban components that also influence the urban climate (like vehicles, green spaces, etc.). In a future perspective, the inclusion of other types of materials may be also important.