What is the temperature?

The temperature measured in a place where outdoor air circulates and is not exposed to direct sunlight.

In meteorology, the physical quantity representing the degree of air heat and cold is called temperature, which is referred to as temperature for short. The international standard unit for temperature measurement is Celsius (℃).

The temperature mentioned in the weather forecast refers to the air temperature measured in the open air without direct sunlight (usually measured by blinds). The highest temperature is the highest temperature in a day, generally appearing in14-15; The lowest temperature is the lowest temperature in a day, usually before sunrise.

Extended data

Influencing factors:

1, natural factors

The temperature in a certain place changes periodically not only because of the change of solar radiation, but also because of the movement of the atmosphere rather than periodically. The change of actual temperature is the result of the interaction between these two aspects. If the former plays a big role, the temperature changes periodically; On the contrary, it shows an aperiodic change.

However, from the general trend and most cases, the periodicity of daily and annual temperature changes is still the main one. Various components in the heat balance, such as radiation difference, latent heat and sensible heat exchange, are affected by different control factors. Astronomical factors such as latitude and season have obvious zonal and periodic characteristics.

However, the nature, topography and weather conditions of the underlying surface, such as cloud cover and atmospheric humidity, all have non-zonal characteristics. At the same time, the influence of these factors is different in different places, so the temperature distribution caused by the change of heat budget is also uneven.

2. Human influence

(1) and the characteristics of urban underlying surface (the interface between atmospheric bottom and 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.

(2) 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.

(3) The influence of artificial heat source.

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

(4) The urban natural underlying surface is reduced.

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.

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