Which condition is favorable for the development of thunderstorms?

The development of thunderstorms is most favorable under conditions of unstable air. Unstable air is characterized by warm, moist air at the surface that can rise rapidly when it becomes less dense than the cooler air above it. This buoyancy allows for significant vertical development, leading to the formation of cumulus clouds, which can evolve into cumulonimbus clouds - the type of clouds associated with thunderstorms.

When the air is unstable, it creates an environment where convection can occur, facilitating the vertical movement of air masses. As the warm air rises, it cools, condensing the moisture it holds and forming clouds. The vigorous Updrafts associated with this process can lead to the development of thunderstorms, which are characterized by heavy precipitation, lightning, and sometimes severe weather phenomena such as hail or tornadoes.

In contrast, low relative humidity would limit the amount of moisture available for cloud formation, stable air inhibits vertical movement and thus reduces the potential for convection necessary for thunderstorm development, and a weak lifting agent would not provide the upward motion required to initiate significant cloud formation or thunderstorm activity. Therefore, unstable air is the crucial condition that supports the formation of thunderstorms effectively.