Black fog, also known as "pea soup fog," occurs due to air pollution containing soot particulates and sulfur dioxide. It is a very thick fog, often appearing yellowish, greenish, or blackish in color.
Here's a breakdown of the reasons:
- Air Pollution: The primary cause is high concentrations of pollutants in the air.
- Soot Particulates: These tiny black carbon particles, primarily from burning fossil fuels (coal, oil, etc.), give the fog its dark color.
- Sulfur Dioxide (SO2): This poisonous gas, also released during the burning of fossil fuels, contributes to the formation of acidic fog and can further darken its appearance. Sulfur dioxide can also react with other substances in the air to create sulfate aerosols, which can contribute to the density and color of the fog.
Therefore, black fog is a direct result of industrial activities, vehicle emissions, and other sources that release significant amounts of pollutants into the atmosphere. The combination of soot and sulfur dioxide creates the thick, dark, and often dangerous conditions associated with this type of fog.
