Surface inversion, also known as a temperature inversion near the ground, occurs when the air temperature increases with altitude in the lower atmosphere, contrary to the normal condition where temperature decreases with height.
Understanding Temperature Inversions
Normally, the air temperature decreases as you go higher in the atmosphere. This is because the sun heats the ground, which then warms the air directly above it. However, under certain conditions, this pattern reverses, leading to a temperature inversion.
How Surface Inversions Develop
Surface inversions most often develop on clear, calm nights due to radiational cooling. Here's how:
- Radiational Cooling: The Earth's surface radiates heat into space, especially on clear nights when there are no clouds to trap the heat.
- Ground Cooling: The ground cools down rapidly.
- Air Cooling: The air in direct contact with the cold ground also cools, becoming colder than the air above it.
- Inversion Formation: This results in a layer of cool air near the surface with warmer air above, creating a temperature inversion.
Factors Contributing to Surface Inversions
Besides clear, calm nights, other factors can contribute to surface inversions:
- Snow Cover: Snow reflects sunlight, leading to less ground heating during the day and enhanced radiational cooling at night.
- High Pressure Systems: Subsiding air associated with high-pressure systems can suppress vertical mixing and trap cool air near the surface.
- Valleys: Cold air can drain into valleys at night, creating a pool of cold air at the bottom and a surface inversion.
Implications of Surface Inversions
Surface inversions can have significant implications:
- Air Pollution: They trap pollutants near the surface, leading to poor air quality. The stable air prevents pollutants from dispersing, concentrating them at ground level.
- Fog Formation: The cool, stable air can lead to fog formation, especially in humid areas.
- Reduced Visibility: Fog and trapped pollutants can significantly reduce visibility, impacting transportation and other activities.
- Frost Formation: Enhanced radiational cooling near the surface increases the likelihood of frost formation, potentially damaging crops.
Table Summarizing Surface Inversions
| Feature | Description |
|---|---|
| Definition | Temperature increasing with altitude near the ground |
| Typical Conditions | Clear skies, calm winds, long nights, snow cover, high pressure, valleys |
| Formation | Radiational cooling of the ground and subsequent cooling of the air near it |
| Impacts | Air pollution, fog formation, reduced visibility, frost formation |
In summary, a surface inversion is a meteorological phenomenon where the normal decrease in temperature with altitude is reversed near the ground, leading to a layer of cooler air trapped beneath warmer air. This condition often arises from radiational cooling on clear, calm nights and can have notable effects on air quality and weather.
