An ascending parcel of air continues to rise to a considerable height when:

An ascending parcel of air will continue to rise to a considerable height when it experiences reduced stability. This relates to the concept of atmospheric stability, which determines whether a parcel of air will rise or sink. When stability is reduced, often due to warmer air at the surface or the presence of a thermal, the buoyancy of the parcel increases, allowing it to ascend further into the atmosphere.

In an unstable environment, any upward movement of the air parcel results in it being warmer and less dense than the surrounding air, enabling it to continue rising. This situation can be influenced by factors such as solar heating of the surface, lifting mechanisms, and differences in temperature and humidity that can create thermal currents.

In scenarios where the temperature increases with height, or when temperature and humidity are not constant, these factors can sometimes indicate stability rather than instability. Similarly, marked variations in pressure over a horizontal area can lead to horizontal winds and turbulence but do not necessarily facilitate the continued vertical ascent of a parcel of air. Thus, the primary factor in ensuring continuous ascent is the reduced stability of the surrounding atmosphere.