What is Temperature Inversion?
Under normal circumstances, the temperature in the troposphere declines at a rate of 1 degree per 165 metres as height rises. This is referred to as the usual lapse rate. However, in rare circumstances, the scenario is reversed, and the temperature rises rather than falls with height. Temperature inversion is the term for this.
Temperature inversion refers to a reverse of the troposphere's typical temperature pattern. A warm air's layer sits over the cold air layer in this meteorological occurrence.
After understanding what is temperature inversion, let us move further to what causes temperature inversion and temperature inversion diagram. Here is the temperature inversion diagram:
(Image will be Uploaded soon)
But what Causes Temperature Inversion?
It is caused by static atmospheric conditions, although it can also be caused by horizontal or vertical air movement. Temperature inversions are usually short-lived, but they are pretty common.
Favourable Conditions for Temperature Inversion
Long winter nights: Heat loss from the earth’s surface due to terrestrial radiation may exceed the amount of incoming solar radiation during the night.
When the sky is clear and there are no clouds, heat is lost more quickly through terrestrial radiation.
Dry air near the ground surface: It prevents radiated heat from the Earth's surface from being absorbed.
Slow air movement: There is no heat transmission or mixing in the lower levels of the atmosphere due to this.
Snow-covered ground surfaces result in the most significant heat loss due to the reflection of incoming solar energy.
Temperature Inversion Effects
Here are some common temperature inversion effects:
Cloud formation, visibility, and precipitation are all influenced by inversions.
The upward movement of air from the layers below is slowed by an inversion. As a result, convection caused by below-inversion heating is limited to levels below the inversion. Dust, smoke, and other air pollutants are also limited in their spread.
Convective clouds cannot develop high enough to produce showers in areas where there is a strong low-level inversion.
Due to the accumulation of dust and smoke particles below the inversion, visibility may be considerably decreased. Fog is typically prevalent towards the base of an inversion because the air is cold.
Temperature diurnal variations are also affected by inversions. The difference between the hours of the day and the hours of the night is usually relatively minor.
Types of Temperature Inversion
Here are the common types of temperature inversion:
1. Intermountain Valley temperature inversion (Air Drainage Type of Inversion)
With elevation, the temperature in the lower layers of the air can sometimes rise rather than fall. This is a common occurrence on a sloping surface. The surface here rapidly radiates heat back to space and cools down faster than the top layers. The lower cold layers condense and become heavier as a result.
They travel towards the bottom of the sloping surface, where the cold layer settles as a zone of low temperature, while the top layers are somewhat warmer. Temperature Inversion is a circumstance in which the vertical temperature distribution is the polar opposite of the typical vertical distribution.
In other words, during a temperature inversion, the vertical temperature is inverted. In the middle and upper latitudes, this type of temperature inversion is particularly strong. It can also be influential in areas with steep mountains or deep valleys.
2. Ground Inversion (Surface Temperature Inversion)
A ground inversion occurs when the air gets chilled by contact with a colder surface until it is cooler in comparison to the overlying atmosphere; this happens most often during clear nights when the ground cools very quickly due to radiation. Fog may also form as the temperature of the surface air falls below the level of the dew point.
This type of temperature inversion is prevalent at higher latitudes. In the lower and medium altitudes, a surface temperature inversion occurs during cold nights and is removed throughout the day.
3. Subsidence Inversion (Upper Surface Temperature Inversion)
When a significant layer of air falls, a subsidence inversion occurs. As a result of the increased atmospheric pressure, the layer is compressed and heated, lowering the temperature lapse rate. When the air mass decreases, higher altitude air becomes warmer than lower altitude air, resulting in a temperature inversion.
In winter (dry atmosphere), subsidence inversions are widespread over the subtropical oceans and the northern continents; these locations generally contain subsiding air due to their location under massive high-pressure centres. Because it occurs in the upper atmosphere, this temperature inversion is known as upper surface temperature inversion.
4. Frontal Inversion (Advectional type of Inversion of Temperature)
A frontal inversion happens when a cold air mass undercuts a warm air mass and raises it aloft (Cold and Warm Fronts: we'll go over that later); a front between the two air masses then has hot air above it and cold air beneath.
This type of inversion has a steeper slope than others, which are virtually level. Furthermore, humidity levels may be high, and clouds may be present just above it. This form of inversion is unstable, and as the weather changes, it disintegrates.
Economic Implications of Temperature Inversion
The air temperature near the valley bottom can drop below freezing at times, while the air at higher altitudes remains quite warm. As a result, the trees on the lower slopes are frost-bitten, while those on the higher slopes are unaffected.
Air contaminants such as dust particles and smoke do not disperse in the valley bottoms due to temperature inversion. Houses and farms in intermountain valleys are located along the upper slopes, avoiding the cold and foggy valley bottoms because of these conditions. Coffee growers in Brazil and apple growers and hoteliers in India's Himalayan mountain states shun lower slopes.
Fog reduces visibility, which has an impact on plants and human settlements.
Less rain as a result of the stable weather.
Above, we discussed what temperature inversion is and the types of temperature inversion. You can check more details and definitions on temperature inversion pdf versions too.
FAQs on Temperature Inversion
1. What exactly is a temperature inversion in geography?
A temperature inversion is an atmospheric condition where a layer of warm air sits on top of a layer of cooler air near the ground. This is the opposite of the normal pattern, where air gets colder as you go higher. The warm air acts like a lid or cap, preventing the cooler air below from rising.
2. What are the main causes of a temperature inversion?
Temperature inversions can be caused by several factors, often working together. The most common causes include:
- Radiational Cooling: On long, calm nights, the ground loses heat rapidly, cooling the air layer directly above it.
- Valley Inversions: In hilly areas, cold, dense air sinks and settles in the bottom of valleys overnight, with warmer air remaining above the valley ridges.
- Frontal Inversions: This occurs when a cold air mass pushes under a warm air mass, forcing the warm air to rise over the cooler air.
3. How are the air layers arranged during a temperature inversion?
During a temperature inversion, the typical atmospheric layers are flipped. At the bottom, near the Earth's surface, there is a layer of cool, dense air. Directly above this is a layer of warmer, lighter air. This warmer layer acts as a stable barrier, trapping the cool air and anything in it (like pollutants or moisture) underneath.
4. Can you give a common, real-world example of temperature inversion?
A classic example is seeing smoke from chimneys flatten out and spread sideways instead of rising on a cold morning. This happens in valleys where cold air has settled overnight. The smoke rises until it hits the warmer air layer above (the inversion layer) and can't go any higher, so it is forced to spread out horizontally within the trapped cold air.
5. How does a temperature inversion make smog and air pollution worse?
The layer of warm air during an inversion acts like a lid, trapping pollutants from cars, factories, and wood smoke in the cold air near the ground. Because the air cannot mix vertically and disperse the pollutants, they become highly concentrated. This concentration of pollutants is what creates dense, harmful smog and leads to very poor air quality.
6. How does a temperature inversion affect humans?
The trapping of pollutants during an inversion can cause or worsen respiratory problems like asthma. The stale, polluted air can lead to coughing, chest tightness, and irritation of the eyes and throat. Extremely poor visibility caused by the trapped smog can also lead to transportation accidents.
7. What is the main difference between the normal lapse rate and a temperature inversion?
The key difference is the direction of temperature change with altitude. The normal lapse rate describes the standard condition where air temperature decreases as you go higher. In contrast, a temperature inversion is an exception where the temperature actually increases with altitude for a certain layer.
8. Is temperature inversion ever considered good, or is it always harmful?
While mostly known for its harmful effect of trapping pollution, an inversion can occasionally be beneficial in agriculture. For example, a slight ground inversion can prevent frost from forming on fruit trees or crops on a hillside. The coldest air sinks to the bottom of the valley, leaving the plants on the slopes in a slightly warmer layer of air, protecting them from a killing frost.
9. Why are calm, clear winter nights the perfect conditions for a temperature inversion to form?
On a clear night, there are no clouds to trap heat, so the ground radiates heat and cools down very quickly. On a calm night, there is no wind to mix the air. This allows the air right next to the cold ground to become very cold and dense, while the air above remains relatively warm, creating a strong and stable ground inversion.
10. How does a temperature inversion influence local weather like fog and frost?
A temperature inversion traps moisture near the cool ground. If the temperature in this trapped layer drops to the dew point, this moisture condenses to form thick ground fog or smog. It also promotes the formation of frost because the ground surface can become much colder than the air just a few feet above it, causing water vapour to freeze directly onto surfaces.
