According to monitoring documents of recent decades, the city’s temperature is always higher than in the suburbs. This is known as the “heat island effect of the city.” For example, the average annual temperature in Shanghai, New York, is 1.1 ° C higher than in the suburbs. Beclin is 1 ° C higher than suburban, Moscow, Paris 0.7 ° C higher, and Washington 0.6 ° C higher. Some days are tall. February 13 – 1979 in Shanghai was 4.5 ° C higher than in the suburbs. At noon on July 10, 1981, Beijing’s temperature was 4.7 ° C higher than the suburbs. On the evening of July 4, 1972, in Wonkơhua, Canada, a very high heat island effect has been measured once in the city, 11 ° C higher than the suburbs. That means that the suburbs of Wonkơhua are still a slightly cold early spring climate, while the city has already had a summer climate.
Why are temperatures in the city always higher than in the suburbs?
There are many causes of temperature in a city, mainly to the following.
One is the centralized plant, the use of industrial heat is very low, plus the exhaust gases of cars and motor vehicles continuously emit. According to the measured results of the Investigation Department of Remote Aeronautical Investigation of Thuong Hai City, it is found that, along the banks of To Chau river in Pho Da region and east of Duong Pho area, south of Huangpu river, the climate is daily. Nights are higher than around from 3 – 4 ° C. These three areas are dense factory areas that consume a lot of energy.
Second, bricks, cement, and asphalt emit a lot of heat from the sun, day and night.
Third, the city has a good drainage system. After the rain, the water is quickly drained, making the ground dry, so the heat used to evaporate the water is very little.
Fourth, the city’s large buildings are dense, not well ventilated, so it is not conducive to the diffused heat.
Also, in the city sky is often floating haze. These clouds of smoke retain heat at night. So the heat island effect of the city compared to daytime is more pronounced. The factory holidays are not working, the heat is less discharged, so the city’s heat island effect is a little better.
Because the city temperature is higher than the suburbs, the people can’t stand it, especially on days with high heat island effect, less wind, and more tired. According to research, in general, the human body does not sweat in environments lower than 25 ° C, above and below 28 ° C, lustful when the temperature reaches 29 – 30 ° C, sweat a lot. No wonder in the summer, city residents race to the sea, mountains, or suburbs to avoid the heat.