What is the symbol of the horizontal 8 with three dots above and below?

Represents the weather "haze". Also known as haze and haze, it refers to the turbidity phenomenon of unknown reasons caused by the suspension of a large number of particles such as smoke and dust. The core substance of smog is dust particles suspended in the air, which are called aerosol particles in meteorology.

Haze contains hundreds of atmospheric chemical particles, which invade the human respiratory tract and lungs when people are unprepared, thus causing respiratory diseases, cardiovascular diseases, blood systems, reproductive systems and other diseases.

Different from the common signs of sunny and rainy clouds, the meteorological symbols of fog and haze are somewhat "difficult to understand". Fog with water content as high as 90% is marked with three horizontal bars, and haze with water content below 80% is marked with "8", which looks a bit like an infinite symbol in mathematics. The water content is between 80% and 90%, which is a mixture of fog and haze, and the main component is haze.

Extended data

In foggy weather, ordinary citizens should do: old people and children should go out less, drive and walk carefully, and pay attention to exercise. In moderate and severe haze weather, a large number of aerosol particles harmful to human health accumulate in the air near the ground, which can directly enter and adhere to the upper and lower respiratory tract and lung lobes of the human body, causing diseases such as rhinitis and bronchitis, and can also induce lung cancer in this environment for a long time.

Therefore, elderly children with weak resistance and people susceptible to respiratory diseases should go out as little as possible, or reduce outdoor activities, and wear masks to protect their bodies when going out. Moderate and severe smog weather is easy to stimulate the human respiratory and circulatory system, especially in the morning when the air quality is poor, people are easy to sprain their bodies during exercise and induce myocardial infarction and pulmonary heart disease.

Industrial masks and medical masks have a certain protective effect on fine particles. Ordinary cotton and cotton masks can filter out large particles such as pollen and have no protective effect on fine particles such as PM2.5

Activated carbon mask, this mask adds an activated carbon layer with adsorption function, but the activated carbon layer only increases the filtering effect on odor, but it can not increase the protection effect on particulate matter.

Industrial dust mask has a good protective effect on fine particles, but it has a large respiratory resistance. If you wear it for a long time, you will have symptoms such as dizziness and nausea. Medical mask. The elderly, children and other people with respiratory diseases or weak constitution should wear low-resistance and head-mounted masks.

References:

Baidu Encyclopedia-Smog (a large number of particles in the air that cannot be distinguished by the naked eye)