Define Lifting Condensation Level for a parcel of air. b. Consider a parcel of air of temperature 30°C at sea level with dew point temperature of 18.5°C. Derive the lifting condenstation level (LCL) of this parcel.
The Correct Answer and Explanation is :
Lifting Condensation Level (LCL) Definition:
The Lifting Condensation Level (LCL) is the height at which an air parcel, when lifted adiabatically, becomes saturated and condensation begins. This occurs when the parcel cools to its dew point temperature, at which the relative humidity reaches 100%. At this level, cloud formation typically begins.
Derivation of LCL:
To determine the LCL for a given air parcel, we use the empirical formula:
[
LCL \approx \frac{(T – T_d)}{8} \times 100
]
where:
- (T) = Initial temperature of the air parcel (°C)
- (T_d) = Dew point temperature (°C)
- The constant 8°C/km represents the approximate rate at which temperature and dew point converge when lifted.
Given:
- (T = 30°C)
- (T_d = 18.5°C)
[
LCL = \frac{(30 – 18.5)}{8} \times 100
]
[
LCL = \frac{11.5}{8} \times 100
]
[
LCL = 1.4375 \times 100
]
[
LCL \approx 1440 \text{ m} \text{ or } 1.44 \text{ km}
]
Explanation:
The LCL represents the level where air reaches saturation, leading to cloud formation. As the air parcel rises, it expands and cools adiabatically at the dry adiabatic lapse rate (DALR) of 10°C/km. However, the dew point temperature also decreases but at a lower rate (~2°C/km). When the air parcel reaches a height where the temperature equals the dew point temperature, condensation begins.
This process is crucial in meteorology as it determines the cloud base height. If an air parcel is lifted above the LCL, further cooling results in condensation and cloud formation. The LCL is important for predicting weather patterns, thunderstorms, and cloud development.
Below is a graphical representation of the Lifting Condensation Level (LCL).
Here is the generated image illustrating the Lifting Condensation Level (LCL) process. Let me know if you need any modifications or further explanations!
