When the ambient lapse rate is greater than the dry adiabatic lapse rate, the atmosphere is said to be:

✅ Explanation:
When
ELR > ALR ⇒ Super- adiabatic lapse rate ⇒ Unstable Environment
ELR < ALR ⇒ Sub – adiabatic lapse rate ⇒ Stable Environment
ELR = ALR ⇒ Neutral Condition
ELR is negative ⇒ Inversion
Adiabatic Lapse Rate (ALR) is – 9.8oC per 1000 m rise

🔴Additional Information:
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)