Correct Answer - Option 1 : ELR >> DALR
Explanation:
Lapse rate. In the troposphere, the temperature of the surrounding air normally decreases with an increase in altitude (height). This rate of change of temperature is called the lapse rate.
This rate differs from place to place and time to time. Hence the prevailing lapse rate at a particular time and the particular place can be determined by sending up a balloon equipped with a thermometer and a recording mechanism, which is known as prevailing lapse rate or environment lapse rate (ELR)
The adiabatic lapse rate is the rate at which the temperature of an air parcel changes in response to the compression or expansion associated with elevation change, under the assumption that the process is adiabatic, i.e., no heat exchange occurs between the given air parcel and its surroundings.
Since a rising parcel of emitted smokes, will normally, neither be fully dry nor fully saturated, the actual adiabatic lapse rate (ALR), representing cooling of emitted smokes is in between dry adiabatic rate ( 9.8 ° C/km) and wet adiabatic rate (6 ° C/km)
When ELR > ALR environment is unstable.
1) Looping Plume: Occurs in a super adiabatic environment.
Note:
It is observed in an unstable environment where ELR > ALR and is characterized by rapid mixing of the pollutants into the atmosphere requiring higher stacks.
Looping plume has a wavy character and occurs in the super–adiabatic environment; which produces a highly unstable atmosphere, because of rapid mixing and due to rapid mixing the mixing height would be maximum.
During the high degree of turbulence, the dispersion of the plume would be rapid, yet higher concentrations near the ground may occur due to turbulence before the dispersion is finally completed.
