The main difference between environmental lapse rate and adiabatic lapse rate is that the environmental lapse rate represents the actual temperature change with altitude observed in the atmosphere. In contrast, the adiabatic lapse rate describes the theoretical temperature change of a rising or descending parcel of air under adiabatic conditions.
Understanding the behavior of temperature in the Earth’s atmosphere is crucial for various fields, including meteorology, climatology, and aviation. Environmental and adiabatic lapse rates are two important concepts in this regard.
Key Areas Covered
1. What is Environmental Lapse Rate
– Definition, Features
2. What is Adiabatic Lapse Rate
– Definition, Features, Types
3. Similarities Between Environmental Lapse Rate and Adiabatic Lapse Rate
– Outline of Common Features
4. Difference Between Environmental Lapse Rate and Adiabatic Lapse Rate
– Comparison of Key Differences
Key Terms
Adiabatic Lapse Rate, Dry Adiabatic Lapse Rate, Environmental Lapse Rate, Moist Adiabatic Lapse Rate
What is Environmental Lapse Rate
The environmental lapse rate (ELR) is a fundamental concept in meteorology that describes the change in temperature with altitude in the Earth’s atmosphere. It is crucial in understanding weather patterns, atmospheric stability, and vertical air movements. The ELR represents the actual temperature change observed in the atmosphere as one ascends or descends in altitude. It is measured by examining the vertical temperature gradient, which quantifies the rate at which temperature decreases or increases with increasing altitude. On average, the ELR is around 6.5 degrees Celsius per kilometer (3.5 degrees Fahrenheit per thousand feet). However, several factors influence the environmental lapse rate. Solar radiation is a primary driver, as it provides the energy that warms the Earth’s surface and subsequently affects the atmosphere’s temperature profile. The amount and angle of solar radiation received at different latitudes and times of the day contribute to variations in the ELR.
The environmental lapse rate also influences cloud formation and precipitation. As air rises, it expands due to decreasing atmospheric pressure, leading to adiabatic cooling. The dry adiabatic lapse rate governs the rate at which the temperature decreases during this expansion.
What is Adiabatic Lapse Rate
The adiabatic lapse rate is a fundamental concept in atmospheric science that describes the temperature changes experienced by a parcel of air as it rises or descends in the atmosphere without exchanging heat with its surroundings. This concept is crucial for understanding vertical air motions, cloud formation, and atmospheric stability. There are two types of adiabatic lapse rates: dry adiabatic lapse rate and moist adiabatic lapse rate.
Dry Adiabatic Lapse Rate (DALR)
The dry adiabatic lapse rate refers to the rate at which the temperature of a parcel of dry air changes as it ascends or descends in the atmosphere. Under ideal conditions, this lapse rate is approximately 9.8 degrees Celsius per kilometer (5.4 degrees Fahrenheit per thousand feet). It is considered a theoretical constant and provides a baseline for understanding the behavior of dry air masses in the atmosphere.
When a parcel of air rises, it expands due to decreasing atmospheric pressure. This expansion causes the parcel to cool at a constant rate without exchanging heat with its surroundings. Conversely, when a parcel of air descends, it is compressed, increasing temperature without heat exchange. The ideal gas law and the principles of adiabatic processes govern these temperature changes.
The dry adiabatic lapse rate is an essential tool for understanding atmospheric stability. If the environmental lapse rate (ELR) is less than the dry adiabatic lapse rate, the atmosphere is considered stable. In this scenario, a parcel of air displaced from its original position will tend to return to its initial position, inhibiting vertical air motions and leading to calm weather conditions.
Moist Adiabatic Lapse Rate (MALR)
The moist adiabatic lapse rate describes the temperature changes experienced by a saturated parcel of air as it rises or descends in the atmosphere. It takes into account the release of latent heat associated with the condensation of water vapor within the parcel. The moist adiabatic lapse rate is influenced by the amount of moisture in the air and the rate of condensation.
Understanding the adiabatic lapse rate is vital for meteorologists and atmospheric scientists as it helps interpret weather patterns and predict atmospheric conditions. Weather balloons equipped with radiosondes are commonly used to measure temperature, humidity, and pressure profiles in the atmosphere, allowing for calculating lapse rates.
Similarities Between Environmental Lapse Rate and Adiabatic Lapse Rate
- Both environmental lapse rate and adiabatic lapse rate describe the change in temperature with increasing altitude in the Earth’s atmosphere.
- Both lapse rates represent vertical temperature gradients.
- Moreover, they influence various atmospheric processes.
Difference Between Environmental Lapse Rate and Adiabatic Lapse Rate
Definition
Environmental lapse rate (ELR) refers to the rate at which the temperature of the Earth’s atmosphere changes with increasing altitude in a specific location and time. Adiabatic lapse rate, on the other hand, refers to the rate at which the temperature of a parcel of air changes as it rises or descends in the atmosphere without exchanging heat with its surroundings.
Heat Exchange
Environmental lapse rate includes the effects of heat exchange between the air parcel and its surroundings. In contrast, the adiabatic lapse rate, by definition, assumes no heat exchange between the air parcel and its surroundings.
Types
ELR is a generalized term that encompasses the temperature changes observed in the actual atmosphere, whereas adiabatic lapse rate includes two main types: Dry Adiabatic Lapse Rate (DALR) and Moist Adiabatic Lapse Rate (MALR).
Application
Moreover, ELR is widely used in meteorology and climatology to understand atmospheric stability, cloud formation, and weather patterns. Meanwhile, adiabatic lapse rates, especially the moist adiabatic lapse rates, are crucial for understanding cloud formation, precipitation, and convective weather phenomena.
Conclusion
The main difference between environmental lapse rate and adiabatic lapse rate is that the environmental lapse rate represents the actual temperature change with altitude observed in the atmosphere, while the adiabatic lapse rate describes the theoretical temperature change of a rising or descending parcel of air under adiabatic conditions.
Reference:
1. “Lapse Rate | Meteorology.” Encyclopedia Britannica
2. “Adiabatic Lapse Rate – An Overview.” ScienceDirect Topics
Image Courtesy:
1. “Mountain Peak over Clouds” (CC0) via Pexles
2. “LCL-determination” By Frogsaregreen – Own work (CC BY-SA 3.0) via Commons Wikimedia
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