Inversion fog is a type of fog that forms when air near the ground is cooled, often due to an atmospheric inversion where warmer air sits above colder air. This process is clearly explained below.
Formation of Inversion Fog
Inversion fog develops through a specific process involving air, temperature, and humidity.
- Cooling of Air: Air passing over cold water or a cold surface gets chilled.
- As the air cools, its capacity to hold moisture decreases.
- Increased Humidity: The relative humidity of the chilled air rises.
- The air becomes more saturated with water vapor.
- Trapping under Inversion: The cool, moist air becomes trapped below a layer of warmer air.
- This is an atmospheric inversion.
- Stratus Layer Formation: Nocturnal cooling may then cause a stratus layer to form.
- This layer builds down to the ground.
- Ground Level Fog: The stratus layer reaching the ground becomes inversion fog.
Characteristics of Inversion Fog
- Ground-Level: This type of fog forms at the surface.
- Trapped Air: It's created when cool air is trapped below warmer air.
- High Humidity: It is characterized by high relative humidity.
- Nocturnal Development: Often forms during the night or early morning when cooling is greatest.
Example Scenario:
Imagine a lake of cold water. Air moves across this cold water, which chills it. This chilled air becomes more humid, as it's closer to saturation. This now-cold air is denser than the warmer air above it, which creates an inversion. Then, further cooling at night, as the surface cools down, leads to a layer of stratus cloud forming above the ground. Eventually, this cloud forms right at the surface, becoming an inversion fog.
Key Takeaways
- Inversion fog happens when cool, moist air is trapped under a warmer layer, often leading to ground-level fog.
- The process involves air cooling, humidity increasing, and an atmospheric inversion.
