What is the heat island effect?

The heat island effect refers to the phenomenon that the temperature of an area is higher than that of surrounding areas. Expressed by the difference in air temperature between two representative measuring points (i.e. heat island intensity). There are two main types: urban heat island effect and Qinghai-Tibet Plateau heat island effect.

The urban heat island effect is one of the typical features of urban climate. It is the phenomenon that urban temperatures are higher than those in suburban areas. It means that when a city develops to a certain scale, due to changes in the nature of the city's underlying surface, air pollution, and the emission of artificial waste heat, the temperature in the city is significantly higher than in the suburbs, forming a phenomenon similar to a high-temperature island.

The main reasons are the comprehensive impact of dense urban population, heat dissipation from factories and vehicles, release of residents’ daily energy, urban building structure and underlying surface characteristics.

Extended information

Climate conditions are the external factors that cause the urban heat island effect, while urbanization is the internal cause of the formation of heat islands. It is generally believed that there are three causes of heat islands:?

1. The surface properties of cities and suburbs are different, and the thermal properties are quite different. Urban areas have low reflectivity, absorb more heat, consume less heat through evaporation, conduct heat quickly, and lose heat slowly through radiation. The opposite is true in suburban areas.

2. Urban areas emit more man-made heat than suburban areas. ?

3. The concentration of air pollutants in urban areas is high and there are many aerosol particles, which play a role in thermal insulation to a certain extent. ?

Atmospheric pollution plays a very complex and special role in the urban heat island effect. The concentration of air pollutants from industrial production, transportation and daily life is particularly high in urban areas, which greatly weakens direct solar radiation during the day, slows down the temperature rise in urban areas, and reduces heat loss caused by effective long-wave radiation on the urban surface at night, playing a role in thermal insulation. , causing cities to "cool" slower than suburbs, forming a nighttime heat island phenomenon.

Baidu Encyclopedia-Heat Island Effect