Temperature Inversion: Types and Formation

• Temperature inversion occurs when the normal temperature decrease with altitude is reversed.
• This creates a layer of warm air above cooler air.
• It impacts weather, pollution levels, and cloud formation.

Ground (Surface) Inversion

• Forms at night, when the Earth's surface loses heat through radiation.
• Occurs on clear, calm winter nights.
• Air near the ground cools faster than the air above.
• Cold air is trapped near the surface, with warm air above.
• This leads to fog, frost, and smog accumulation.
• Ground inversions are common in valleys and low-lying areas.
• A prime example is foggy winter mornings in North India due to trapped moisture and pollution.

Advection Inversion

• Forms when warm air moves over a cold surface, like land or water, which cools the lower air layer.
• Common in coastal regions where ocean currents cool the air.
• Leads to fog formation and reduced visibility.
• Frequently seen over cold ocean currents such as the California and Benguela Currents.
• Causes stable weather conditions with minimal vertical air movement.
• An example is the San Francisco Fog, where warm, moist Pacific air moves over the cold California Current, forming thick fog.

Frontal Inversion (Cyclonic Inversion)

• Occurs when a warm air mass overrides a cold air mass at a weather front creating an inversion layer at the boundary.
• Found in mid-latitude cyclones and at warm or occluded fronts.
• Leads to cloud formation, precipitation, and stormy weather.
• Prevents vertical mixing of air masses.
• Inversions form along warm fronts before heavy rainfall.

Subsidence Inversion

• Caused by descending air in high-pressure systems, which compresses and warms the air up.
• Prevents the mixing of lower and upper air layers.
• Common in subtropical high-pressure belts (around 30° N and 30° S).
• This creates stable, dry, and warm conditions.
• Leads to prolonged dry spells and desert formation.
• Deserts like the Sahara and Kalahari exist due to subsidence inversions.
• It can cause severe air pollution events in cities, for example Los Angeles smog.

Valley Inversion (Topographic Inversion)

• Happens in valleys where cold air drains downward at night becoming trapped under a layer of warm air.
• More common in winter and in mountainous areas
• Leads to frost, persistent fog, and poor air quality.
• Can last for days in deep valleys.
• The Kashmir Valley often experiences prolonged fog and cold waves due to valley inversion.

Effects of Temperature Inversion

• Can create stable weather conditions, reducing storm formation.
• Helps in cloud formation in frontal inversion, leading to rainfall.
• Air Pollution: Traps pollutants, worsening smog in cities.
• Fog and Frost: Reduces visibility and damages crops.
• Health Issues: Increased respiratory problems due to trapped pollutants.

Conclusion

• Temperature inversions play a crucial role in weather and climate patterns.
• Some types contribute to stable weather, while others can lead to pollution buildup and extreme cold conditions.
• Understanding temperature inversions is essential for agriculture, urban planning, and weather forecasting.

Temperature inversion happens when the air temperature increases with altitude instead of decreasing. Ground inversions form at night due to radiative cooling leading to fog and smog. Advection inversions occur when warm air passes over a cold surface, also causing fog.