People can often hear the word "haze". Many people think that fog and haze are the same thing. In fact, there are many differences in both phenomena and causes.
"Fog" is a weather phenomenon in which water vapor in the air condenses into fine water droplets and is largely suspended in the area close to the ground, reducing the visibility of the ground. To put it simply, fog is similar to clouds, which are formed by the condensation of water vapor in the air. When they gather in large numbers, they are called "fog" when they are close to the ground, and clouds are formed when they rise away from the ground. Fog usually forms in the night with sufficient water vapor, stable atmosphere and weak wind, and dissipates in the day with strong sunlight, elevated ground temperature and strong air convection. In the early morning, the sun has just risen, and its energy is not enough to disperse the thick fog.
If you move in heavy fog, you will not only have low visibility, prone to accidents and dangers, but also easily breathe in a large amount of air containing pollutants, which will affect your health. This is because there is usually little wind in foggy days, the air in the whole near ground layer will be very stable, and the upward and downward convective movement is quite weak. At this time, many small particles in the air quietly stay in the air near the ground layer, and some can even dissolve in fog droplets and react chemically with other substances to form pollutants that are more harmful to human health. In addition, the humid environment is also favored by some bacteria. They keep reproducing in small particles or droplets. Once inhaled into the human body, it will have an adverse impact on health.
More serious than fog is haze, also known as haze. It specifically refers to the serious pollution caused by a large number of smoke particles suspended in the air, which usually makes the air appear turbid gray or brownish yellow. The appearance of haze is mainly related to environmental pollution. Especially in densely populated cities, the concentration of pollutants in the air and the sharp increase of all kinds of harmful particles are caused by the domestic waste gas discharged from industrial waste gas, automobile exhaust, garbage accumulation and incineration. At the same time, the urban heat island effect also makes it difficult for particles in the air to emit and discharge into the air, but stay near the ground, which has become an important reason for the frequent occurrence of haze weather.
The difference between fog and haze is that fog usually appears in the early morning, with high humidity, which dissipates rapidly with the increase of sunlight and temperature; Haze can appear at any time, with low humidity and large thickness, which is difficult to dissipate. In many cities, whether in fog or haze, the air near the ground is often polluted to varying degrees, so we should reduce going out in such weather.