Why is foggy weather easy to cause traffic accidents?

Fog is one of the weather that has the greatest influence on human traffic activities. The deterioration of visibility in foggy days is easy to cause traffic accidents. In highway traffic accidents, traffic accidents caused by bad weather such as dense fog account for about a quarter of the total, which not only hinders traffic, but also causes great losses to the country and people's lives and property.

Reason: Because of the uneven shade of fog, it will cause visual error, the driver's judgment of distance and speed is quite different from the actual situation, the sight distance is shortened, and it is easy to collide with the car in front. Especially on the expressway, once a traffic accident happens, it will often cause a chain reaction and eventually form a serious traffic accident.

Second, the impact on health:

In foggy days, the combination of pollutants and water vapor in the air will make it difficult for pollutants to spread and settle, which makes most pollutants gather at the height where people often move. Moreover, some harmful substances will become more toxic when combined with water vapor, such as sulfur dioxide becoming sulfuric acid or sulfite, chlorine hydrolyzing into hydrogen chloride or hypochlorous acid, and fluoride hydrolyzing into hydrogen fluoride.

So the air pollution in foggy days is much more serious than usual. Another reason to emphasize is that the particles that make up the fog core are easy to be inhaled and stay in the human body. The amount of air inhaled during exercise is much more than usual, and a lot of particulate matter will be inhaled in foggy days, which further aggravates the harm of harmful substances to human body.

In this environment for a long time, the human body will inhale harmful substances, consume nutrients, cause internal injuries to the body, and easily induce or aggravate diseases. In particular, some people with environmentally sensitive diseases, such as bronchial asthma, pneumonia and other respiratory diseases, will have normal blood circulation obstruction, leading to cardiovascular diseases, hypertension, coronary heart disease, cerebral hemorrhage and so on.

Heavy fog will aggravate the condition of cardiovascular patients. This is because, on the one hand, the air pressure in dense fog is relatively low, people will feel irritable and their blood pressure will naturally rise. On the other hand, in foggy days, the temperature is often low. Some patients with hypertension and coronary heart disease suddenly go from warm indoor to cold outdoor, and blood vessels expand with heat and contract with cold, which will also increase blood pressure, leading to stroke and myocardial infarction. The air pollution is serious in foggy days, the fog is getting thicker in early winter, the air quality is poor, and the diabetic patients with poor resistance are very likely to have lung and trachea infections, which will aggravate the condition.

In foggy days, due to the decrease of sunshine, insufficient ultraviolet radiation for children, insufficient production of vitamin D in the body, and greatly reduced absorption of calcium, rickets in infants and young children will be seriously caused, which will slow down the growth and development of children. In addition, due to the weak light and low air pressure in foggy days, some people will feel lazy and depressed in foggy days. ?

Third, experts remind:

In foggy days, people should reduce outdoor activities, wear scarves and masks when outdoors, and protect skin, throat, joints and other parts. Middle-aged and elderly people, children and weak people should pay more attention to protection.

Extended data

(1) fog:

When the relative humidity reaches 100%, the water vapor in the air will condense into fine water droplets suspended in the air, which will reduce the visibility on the ground. This weather phenomenon is called fog.

Formation conditions:

One is cooling, and the other is humidifying to increase the water vapor content. There are radiation fog, advection fog, mixed fog and evaporation fog.

(2), and the difference between haze:

1, horizontal visibility is different.

The horizontal visibility of fog is less than1000m. The horizontal visibility of haze is less than 10 km.

2, the relative humidity is different

The relative humidity of fog is more than 90%, and that of haze is less than 80%. 80% ~ 90% of relative humidity is a mixture of haze and fog, but its main component is haze.

3. Different thickness

The thickness of fog is only a few tens to 200 meters. The thickness of smog can reach 3000 meters.

4. Different boundary characteristics

The boundary of fog is very clear, and it may be clear in Wan Li after passing through the "fog zone". There is no clear boundary between smog and clear sky.

5. Different colors

The fog is milky white and blue white. Haze is yellow and orange-gray.

6. Different formation conditions.

Although the formation of fog and haze needs breeze or no wind, and the atmospheric state is stable, that is, there must be an inversion layer, fog needs certain water vapor and cooling conditions to make the air saturated and condense. The formation of smog does not need water vapor and cooling conditions, mainly because the (dry) particles in the air should reach a certain concentration and the relative humidity should not be large.

7. Different ingredients

Fog is mainly composed of tiny water droplets or ice crystals, and the size of water droplets is generally 3 ~ 100 micron. Smog is composed of complex tiny particles invisible to the naked eye, and the diameter of smog particles is only 0.3 ~ 0.6 micron.

8. Daily changes are different.

Fog usually appears most easily from midnight to early morning, and dissipates quickly after sunrise. The diurnal variation characteristics of haze are not obvious. When the air mass changes little and the atmospheric stratification is stable, it lasts for a long time.

9. Seasonal changes are different

There may be fog all year round in our country. Most areas are foggy in autumn and winter, but foggy in spring and summer. Smog has obvious seasonal changes in most parts of the country, with more in winter and less in summer, and it is in the middle of spring and autumn.

10, which means different meanings

Generally speaking, fog is a harbinger of weather forecast, such as the proverb "Ten fogs and nine sunny days". Haze is an environmental problem, and its guiding significance in air pollution research and air quality prediction is more important. ?

Baidu encyclopedia-fog