Recently, North China, Huang-Huai and sustained fog and haze, resulting in Beijing, Hebei, serious air pollution. For the essence of “haze”, we look at how scientists explain.
Recently, North China, Huang-Huai and sustained fog and haze, resulting in Beijing, Hebei, serious air pollution. It is reported today (the 11th) during the day, north south, the Huang-Huai north-central Shaanxi weather conditions off the middle ground is still not conducive to clear air pollutants in some areas with mild to moderate haze, local severe haze. Start at night, with the cold air eastward south, fog and haze in these areas will be significantly reduced or disappear.
What is a “fog”? What is the “haze”?
Fog: Under adequate moisture, the breeze and the atmosphere stable, if the air near the ground is cooled to a certain extent, water vapor in the air will condense into tiny droplets suspended in the air, so that the ground level of visibility is less than 1 1000 meters, the weather phenomenon known as fog. It is due to a cloud caused by temperature decrease, the fog can be said that actually the cloud close to the ground.
“Haze, also known as smog (haze), refers to the unexplained phenomenon due to a lot of cloudy smoke, dust and other particles suspended in the formation. Haze of the core material is airborne dust particles called aerosols particles meteorology The air in the dust, sulfuric acid, nitric acid, hydrocarbons and other organic particles also make atmospheric turbidity, blurry vision and lead to the deterioration of visibility, if the horizontal visibility is less than 10 km, the composition of this non-aqueous aerosol system visual range is called haze caused obstacles (Haze) or haze (Dust-haze), the Hong Kong Observatory said the haze (Haze). “
What conditions produce haze is?
Fog is floating in the air, a large number of fine water droplets or ice crystals, forming conditions to be saturated with water vapor with a higher factor. When the relative humidity is often fog up 100% or close to 100%. With air humidity fog have emerged sooner or later, the diurnal variation of the more common or enriched, reduce or even disappear during the day relative phenomenon. Fog when visibility is less than the effective level of 1KM. When the effective horizontal visibility 1 ~ 10KM when called mist.
The formation of haze is mainly the result of a large number of airborne particles and meteorological conditions combined effect, which causes three: ① increase in the level of 方向静 wind phenomenon. The city more to build higher buildings, blocking and friction so romantic city significantly weakened over time. Static wind phenomenon increased dilution is not conducive to the spread of suspended particles in the atmosphere, it is easy to accumulate in the city and surrounding suburban areas; inversion appears on ② vertical direction. Inversion like a lid covering over the city, this high-altitude low-temperature higher than the temperature inversion phenomenon, making the atmosphere at low altitude air vertical movement is restricted, suspended particles in the air is difficult to drift to the high altitude and were arrested at low altitude and near the ground. ③ increase in suspended particulate matter in the air. With the city’s population growth and industrial development, motor vehicles soared, a substantial increase in pollutant emissions and suspended solids, a direct result of reduced visibility.
Why is it difficult to accurately forecast haze?
Haze in addition to the weather elements forecast data, atmospheric composition data is also very important, sources of data is not readily available. Air pollution near surface meteorological conditions forecast for the requirements of high accuracy meteorological data, and near surface by about surface roughness, vegetation and urban heat island effect and other factors, the relative deviation greater numerical forecast products.
Like haze and fog, mainly in shallow, underlying surface atmosphere is very complex, many factors, forecasting very difficult.
Accurate forecasting haze requires both physical and chemical mechanisms of haze produced an accurate understanding of the need to obtain more ground-based data sources, the data is difficult to accurately obtain.