Why is Shanghai getting hotter and hotter?

The first is the influence of the characteristics of the urban underlying surface (the contact surface between the atmospheric bottom and the surface).

A large number of artificial structures in the city, such as paving the ground and various building walls, have changed the thermal properties of the underlying surface. Urban surface water content is less, and more heat enters the air in the form of sensible heat, which leads to air warming. At the same time, the absorption rate of sunlight on the urban surface is higher than that on the natural surface, which can absorb more solar radiation, so that the air can get more heat and the temperature will rise. For example, in summer, the lawn temperature is 32℃, the canopy temperature is 30℃, the cement floor temperature can reach 57℃, and the asphalt pavement temperature can reach 63℃. These high-temperature objects form a huge heat source, baking the surrounding atmosphere and our living environment. How can they not be spicy?

The second main reason is urban air pollution.

Motor vehicles, industrial production and a large number of people's activities in cities produce a lot of nitrogen oxides, carbon dioxide, dust and so on, which can absorb a lot of energy from the thermal radiation in the environment, produce a well-known greenhouse effect, and cause further warming of the atmosphere.

The third main reason is the influence of man-made heat source.

Factories, motor vehicles, residents' lives, etc. Burning all kinds of fuels consumes a lot of energy. Countless stoves are burning, emitting heat!

The fourth reason is that the natural underlying surface in the city has decreased.

Buildings, squares, roads, etc. It has increased a lot in the city, and the natural factors such as green space and water body have decreased accordingly, releasing more heat and absorbing less heat, and the ability to alleviate the heat island effect has weakened.

Because the increase of artificial structures and the decrease of natural underlying surface are the main reasons of urban heat island effect, increasing the proportion of natural underlying surface in cities through various channels is one of the effective ways to alleviate urban heat island effect.