What is conditional stability in terms of ELR?

Conditional stability refers to a state of the atmosphere where the environmental lapse rate (ELR) falls within a specific range that allows for both stable and unstable conditions depending on the moisture present in the air. When the ELR ranges between approximately 1.3 and 3 degrees Celsius per 1000 feet, the atmosphere is considered conditionally stable.

In this scenario, if an air parcel is forced to rise, and it is saturated (i.e., at 100% relative humidity), it will be warmer than the surrounding air and will continue to rise, exhibiting instability. However, if the air parcel is unsaturated, it will cool at a rate greater than the environmental lapse rate, leading to stability. This dual behavior of the air parcel in response to moisture content is what defines conditional stability in terms of ELR.

Thus, option B accurately captures the essence of conditional stability related to the environmental lapse rate by specifying the critical range.