What is temperature inversion? What are the different types of temperature inversion? What can be the economic implications of temperature inversion?
Temperature Inversion- Normally, temperature decreases with an increase in elevation. It is called the normal lapse rate. At times, the situation is reversed and the normal lapse rate is inverted. It is called Inversion of temperature. Inversion is usually of short duration but quite common nonetheless.
Ideal Conditions for Temperature Inversion
- A long winter night with clear skies. It makes sure that the heat radiated off is more than the incoming radiation.
- Still air to avoid vertical mixing of air at lower levels.
The heat of the day is radiated off during the night, and by early morning hours, the earth is cooler than the air above. Over polar areas, a temperature inversion is normal throughout the year.
Types of Temperature Inversion
1. Air Drainage (Inversion in hills and mountains)
The inversion takes place in the hills and mountains due to air drainage. Cold air at the hills and mountains, produced during the night, flows under the influence of gravity. Being heavy and dense, the cold air acts almost like water and moves down the slope to pile up deeply in pockets and valley bottoms with warm air above. This is called air drainage.
2. Ground Inversion (Surface Temperature Inversion)
A ground inversion develops when air is cooled by contact with a colder surface until it becomes cooler than the overlying atmosphere; this occurs most often on clear nights when the ground cools off rapidly by radiation. If the temperature of surface air drops below its dew point, fog may result.
- Surface Inversion promotes stability in the lower layers of the atmosphere.
- This kind of temperature inversion is very common in higher latitudes.
- A surface temperature inversion in lower and middle latitudes occurs during cold nights and gets destroyed during the daytime.
- Dense fog in the mornings is a common occurrence, especially during the winter season. This inversion commonly lasts for a few hours until the sun comes up and begins to warm the earth.
3. Subsidence Inversion (Upper Surface Temperature Inversion)
A subsidence inversion develops when a widespread layer of air descends. The layer is compressed and heated by the resulting increase in atmospheric pressure, and as a result, the lapse rate of temperature is reduced. If the air mass sinks low enough, the air at higher altitudes becomes warmer than at lower altitudes, producing a temperature inversion. Subsidence inversions are common over the northern continents in winter and over the subtropical oceans; these regions generally have subsiding air because they are located under large high-pressure centres.
4. Frontal Inversion
A frontal inversion occurs when a cold air mass undercuts a warm air mass and lifts it aloft; the front between the two air masses then has warm air above and cold air below. This kind of inversion has a considerable slope, whereas other inversions are nearly horizontal. In addition, humidity may be high, and clouds may be present immediately above it.
Economic Implication of Temperature Inversion
- Inversion of temperature causes frost when the condensation of warm air due to its cooling by cold air below occurs at a temperature below the freezing point. Frost is definitely an economically unfavourable weather phenomenon mainly for crops because fruit orchards and several agricultural crops such as potatoes, tomatoes, peas etc. are totally damaged overnight.
- When fog is formed due to temperature inversion it gets mixed with smokes coming out of houses and chimneys which intensify fogs and become responsible for the occurrence of urban smog. When smog is mixed with air pollutants such as sulphur dioxide it becomes a poisonous and deadly health hazard to human beings. Road and rail transport is also badly affected by the occurrence of dense fog.
- Inversion of temperature causes atmospheric stability which stops upward (ascent) and downward (descent) movements of air. The atmospheric stability discourages rainfall and favours dry condition. The inversion of temperature caused by the subsidence of air resulting in anticyclonic conditions increases aridity. This is why the western parts of the continents situated between 20°-30° latitudes and characterized by anticyclonic conditions represent the most widespread tropical deserts of the world.
Temperature Inversion- Normally, temperature decreases with an increase in elevation. It is called the normal lapse rate. At times, the situation is reversed and the normal lapse rate is inverted. It is called Inversion of temperature. Inversion is usually of short duration but quite common nonetheless.
Ideal Conditions for Temperature Inversion
- A long winter night with clear skies. It makes sure that the heat radiated off is more than the incoming radiation.
- Still air to avoid vertical mixing of air at lower levels.
The heat of the day is radiated off during the night, and by early morning hours, the earth is cooler than the air above. Over polar areas, a temperature inversion is normal throughout the year.
Types of Temperature Inversion
1. Air Drainage (Inversion in hills and mountains)
The inversion takes place in the hills and mountains due to air drainage. Cold air at the hills and mountains, produced during the night, flows under the influence of gravity. Being heavy and dense, the cold air acts almost like water and moves down the slope to pile up deeply in pockets and valley bottoms with warm air above. This is called air drainage.
2. Ground Inversion (Surface Temperature Inversion)
A ground inversion develops when air is cooled by contact with a colder surface until it becomes cooler than the overlying atmosphere; this occurs most often on clear nights when the ground cools off rapidly by radiation. If the temperature of surface air drops below its dew point, fog may result.
- Surface Inversion promotes stability in the lower layers of the atmosphere.
- This kind of temperature inversion is very common in higher latitudes.
- A surface temperature inversion in lower and middle latitudes occurs during cold nights and gets destroyed during the daytime.
- Dense fog in the mornings is a common occurrence, especially during the winter season. This inversion commonly lasts for a few hours until the sun comes up and begins to warm the earth.
3. Subsidence Inversion (Upper Surface Temperature Inversion)
A subsidence inversion develops when a widespread layer of air descends. The layer is compressed and heated by the resulting increase in atmospheric pressure, and as a result, the lapse rate of temperature is reduced. If the air mass sinks low enough, the air at higher altitudes becomes warmer than at lower altitudes, producing a temperature inversion. Subsidence inversions are common over the northern continents in winter and over the subtropical oceans; these regions generally have subsiding air because they are located under large high-pressure centres.
4. Frontal Inversion
A frontal inversion occurs when a cold air mass undercuts a warm air mass and lifts it aloft; the front between the two air masses then has warm air above and cold air below. This kind of inversion has a considerable slope, whereas other inversions are nearly horizontal. In addition, humidity may be high, and clouds may be present immediately above it.
Economic Implication of Temperature Inversion
- Inversion of temperature causes frost when the condensation of warm air due to its cooling by cold air below occurs at a temperature below the freezing point. Frost is definitely an economically unfavourable weather phenomenon mainly for crops because fruit orchards and several agricultural crops such as potatoes, tomatoes, peas etc. are totally damaged overnight.
- When fog is formed due to temperature inversion it gets mixed with smokes coming out of houses and chimneys which intensify fogs and become responsible for the occurrence of urban smog. When smog is mixed with air pollutants such as sulphur dioxide it becomes a poisonous and deadly health hazard to human beings. Road and rail transport is also badly affected by the occurrence of dense fog.
- Inversion of temperature causes atmospheric stability which stops upward (ascent) and downward (descent) movements of air. The atmospheric stability discourages rainfall and favours dry condition. The inversion of temperature caused by the subsidence of air resulting in anticyclonic conditions increases aridity. This is why the western parts of the continents situated between 20°-30° latitudes and characterized by anticyclonic conditions represent the most widespread tropical deserts of the world.
