Although we breathe the same atmosphere and have the same climate, the air temperature in the city and the air temperature in the rural areas differ by a few degrees. When you think that people living in the countryside are sitting cool in their highland houses in the increasing summer temperatures, one cannot help but ask why.
In fact, there is a very simple answer to this, and it opens the door to the point where everything that has happened in recent years is connected: unconscious urbanization and climate change.
The increasing human population negatively affects our quality of life.
Increasing population, one of the biggest problems of our age, brings with it ecological problems. As humans multiply, unpredictable damage occurs in nature. One of these damages is the “urban heat island” effect, which is the answer to the question we asked at the beginning of our article.
First discovered by Luke Howard in 1818, the situation where the average temperature in cities is higher than in the countryside was called the “heat island”. This temperature difference is 3-4 degrees on average. Which is not something to be taken lightly.
The urban heat island effect is a climatic phenomenon caused by urbanization and dense urbanization in large cities.
This situation, which results in the coexistence of surfaces such as concrete, asphalt, cement and high-rise buildings and the reduction of natural soil and vegetation, causes city centers to have higher temperature values.
The urban heat island effect can increase day and night temperature differences. During the day, the sun’s rays heat up more on surfaces such as concrete and asphalt, and this heat raises the overall temperature of the city. This may be due to the negative effects of high air temperatures on human health; It can also lead to problems such as increased energy consumption and decreased urban comfort.
How does this situation occur?
Urban heat islands emerge as a climatic phenomenon different from the natural environment as a result of the construction and intense urbanization in big cities. These islands are regions with higher temperature values than those around the city center. Surfaces such as asphalt, concrete and cement, which replace construction, natural vegetation and open spaces in cities, absorb the sun’s rays more and heat up. The soil and vegetation in natural areas, on the other hand, reflect the sun’s rays better and stay cooler.
Condensation and high-rise buildings in city centers also absorb solar energy and contribute to the increase in temperature by spreading this heat to the environment. Therefore, city centers have higher temperatures than their surroundings.
Transport in cities also contributes to heat generation.
Industrial activities and human influence cause additional heat generation. Resources such as vehicles, factories, heating and cooling systems increase the urban heat island. Freer wind circulation in rural areas helps to cool the air and speed up heat transfer. However, high buildings and narrow streets in cities prevent the free circulation of the wind and cause hot air to accumulate. Thus, an urban heat island is formed.
A study conducted in Istanbul in 2017 revealed the temperature difference between rural and urban areas.
In the research, surface temperature values were calculated with Landsat 8 satellite thermal bands and a land surface temperature distribution map was created. According to the map, the highest temperature was 44.96°C and the lowest temperature was 21.17°C. This map also shows that urban areas trap heat to a large extent compared to green areas.
How can we avoid this situation?
There are, of course, various methods to prevent the urban heat island effect. At the beginning of this, increasing green areas, using reflective surfaces, creating water surfaces and water systems, establishing roof gardens and green roofs, ensuring energy efficiency, promoting sustainable transportation and public transportation play an important role.
Green areas, vegetation and afforestation provide a cooling effect by reflecting the sun’s rays. Reflective surfaces and materials with high reflectivity reflect the sun’s rays more and prevent the surfaces from heating up. The use of energy-efficient heating, cooling and lighting systems reduces energy consumption, while promoting sustainable transportation options reduces traffic congestion and air pollution.
All these measures are used in an integrated manner in urban planning and design processes, offering an effective strategy to reduce the urban heat island effect.
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