Earth is currently in transition from a mostly rural to a mostly urban planet. In 2030 the urbanized areas will be nearly tripled compared to 2000 (Seto et al. 2012). The use of dark building materials, such as asphalt and concrete, leads to a lower albedo in urbanized areas than in natural environment. Lower albedo increases ambient and global temperature. Inversely, the substitution of rooftops’ membranes and pavements’ traditional materials with bright ones and a wise planning of future urban development can increase albedo and support climate stabilization efforts. Here we investigate the potential effect of the increase in albedo on the instantaneous change in radiative forcing in a representative set of European cities. We find a …show more content…
Responsiveness was accounted considering the climatological characteristics of each city. Low cloudiness and high solar radiation make the responsiveness in southern European cities two times higher than in other regions (Figure 1). Figure 1 shows that the mean responsiveness in Scandinavian cities is higher than in north-central European ones. A unitary increase in urban albedo in Scandinavian countries and north-central European ones respectively decreases IRF by 46 and 45 Wm-2. This is explained by the observation that even though the mean incoming solar radiation is lower in Scandinavian cities than in north-central European cities, the clearness index is higher in the firsts than in the seconds.
The effect of the potential increase in urban albedo on IRF is also dependent on the urban areas can be enhanced. In Figure 2 we reported both the responsiveness (indicated by the color bar) and the area of the cities (see also table 1) of the 125 most populous cities.
Second, we calculated the potential increase in average urban albedo (see Methods) understanding the urban morphology – the amount of urban surface for transport and for housing that can be enhanced – of 55 of the cities. Figure 3, including geographical, climatological and morphological information, reports the potential increase in average
2. How do you explain the relationship between the UV Index and latitude? (In other words, why does UV intensity change with latitude?)
From the CER maps (Figure 9), it can be observed that in 2013 ISMR the entire region had witnessed high CER values while other years were partially cover by cloud drops of different radii. The high rainfall intensity during 2013 ISMR could be the manifestation of the high CER values observed during that year compared to the other years (Figure 12). However, the low CER values in the other years can be seen in conjugation with high aerosol loading during that period. Similar trend is also observed in LWP plots for the study area during 2012-15 ISMR (Fig 13). It is evident from the figure 9 that LWP varies from low to high values over the region while, it is more homogeneous in 2014 and 2015 ISMR. The OLR was considerably
It is estimated that over 50% of the world’s population now lives in urban areas and that this will rise to 70% by 2050. Such a change will
EPA, 1992). The UHI phenomenon is created in part by differences between thermal properties (e.g., heat capacity and thermal inertia) of artificial urban surfaces and natural land surfaces. Urban landscapes have reduced vegetative cover. In less developed areas trees and other vegetation cool the air by evapotranspiration, the evaporation of water from the surfaces of leaves and the soil. Because water has a high specific heat, when it undergoes a phase change from liquid to vapor it absorbs a great deal of heat. The loss of latent heat results in a cooling effect on the surface from which it evaporates. Vegetation also cools by shading buildings and blocking solar radiation. Urban surfaces, by contrast, such as roof and paving materials with low reflectivity absorb more solar radiation. These materials store this energy and convert it to sensible heat. Other factors contributing to the onset of UHI include differences in surface albedo, and anthropogenic heat release in the urban
The cryosphere consists of all frozen water on earth. It is found in the high northern and southern latitudes of the planet. The components of the cryosphere include the following: sea ice, glaciers, ice sheets, ice shelves, snow cover, freshwater ice, and frozen groundwater. The cryosphere plays an important role in cooling the planet. The cryosphere, being ice, has a high albedo. The accepted albedo of ice in the cryosphere is .6 or 60%, meaning ice reflects 60% of incoming shortwave radiation. It is important that the cryosphere has a high albedo because it helps the planet to absorb less coming radiation, thus helping to cool the atmosphere. Surfaces such as the open ocean or asphalt roads have a lower albedo; these surfaces absorb more incoming radiation and
How Have Urban Environments Been Made More Sustainable And What More Needs To Be Done for the Future?
The term ‘urban heat island’ refers to the localized increase in temperature associated with an urban area. The UHI is an example of unintentional climate modification when urbanization changes the characteristics of the earth’s surface and atmosphere. It was observed that the UHI effect might result in minimum urban temperatures being 5-6° greater than the surrounding countryside. In the case of London, mean annual temperature was 11°C, while the surrounding countryside was 9.6°C and the suburbs was 10.3°C in the period between 1932—1960. In Kew, London, it has an average of some 72 frost-free days than rural Wisley The reason the city is warmer than the country comes down to a difference between the energy gains and losses of each
An urban heat island is a metropolitan area that suffers from recurrent high temperatures compared to the cooler temperatures of its rural surroundings. There are many factors that contribute to the creation of urban heat islands, but if proper adjustment is done to albedo, architecture, and vegetation, there will be an effective and efficient reduction in city temperatures. Recent studies have shown that urban temperatures are gradually rising, and this dynamic is
Heat wave deaths occur more in cities. The infrastructure of a typical city has brick and mortar buildings, asphalt streets, and tar roofs. As a result, during the daytime they absorb heat and slowly release it at night. The temperatures in urban areas are warmer than rural areas by several degrees night
City residents also face a heightened risk because of warmer temperatures in cities from the urban heat island effect, caused by the mostly paved surfaces that absorb and re-radiate heat and the lack of green spaces and tree cover in these areas.
Cities despite its obvious necessity, have not been put under the microscope of IR for long, it only have been surfacing in the world of international relations in 1991 due to the book by Saskia Sassen entitled The Global
Therefore buildings cool down at night by radiating heat to the sky. This phenomenon also occurs during daytime but is then levelled out by solar radiation.
Generally, meteorological stations are placed only at the urban areas and their follow up is uncertain. In some cases, we need to estimate Evapotranspiration for planning in the large scale; it is rather difficult to classify land use for individual calculation in each land use. Therefore water balance is more suitable to understand the flux in a whole sub basin. The inflow and outflows are determined from stream flow and precipitation measurements and the difference between inflow and outflow over a relatively long period of time is used to estimate evaporation using the
An urban heat island is normally classified as a metropolitan area that is warmer than its environment and the amount of concrete and asphalt a city has greatly contributes to the problem (WTTU). A big city usually contains vast amounts of roads, buildings and asphalt which are materials that absorb heat from the Sun during the day, according to ASU Professor Dr. Brazel. At night, the same constructs will release this heat into the atmosphere generating a significantly warmer environment. At a smaller scale, such as a park or recreational facility, this heat inducing process
Climate change will affect the regional ETref trend. To explore quantify the effects of climatic factors on ETref, sensitivity coefficients for mean air temperature (S(TA)), relative humidity (S(RH)), wind speed (S(WS)), and solar radiation (S(SR)) in each time period of HRB are shown were listed in Table 3. The results revealed that ETref was most sensitive to change of RH, followed by SR, TA and WS. Meanwhile, the value of sensitivity coefficient of WS was lower than that of the other climatic factors, which suggests that ETref had low sensitivity to change of WS. For the entire HRB, the negative sensitivity coefficient was detected for RH that was negatively correlated to the ETref , while the positive values were identified for TA,