3. Stability

Determining Stability » The Parcel Method Unstable

Conceptual animation of air parcel in unstable environment

If a lifted parcel has a higher virtual temperature than the surrounding environment, its density will be less than the environment. In this case, the displaced parcel will accelerate upward away from its original level, and the environment is defined as unstable. Under the same conditions, a sinking parcel will have a lower virtual temperature than its surroundings, and it will accelerate downward away from its original position.