Which factors are critical for tornado formation?

The formation of tornadoes is heavily influenced by the interplay of different air masses, specifically involving warm, moist air and cool, dry air. When warm, moist air rises, it creates instability in the atmosphere. This unstable condition is crucial because it sets the stage for severe thunderstorms, which are often the precursors to tornadoes.

As this warm, moist air collides with cooler, drier air, significant temperature and moisture gradients are established. This clash not only enhances lift but also contributes to the rotation necessary for tornado development. The resulting storm systems can create supercell thunderstorms, which have the potential to produce tornadoes when conditions are favorable.

In contrast, the other options involve weather characteristics that do not contribute to tornado development. Cold air and dry ground conditions are typically not conducive to the instability required for storm formation. High atmospheric pressure and moisture do not create the necessary lifting mechanisms, while stable weather conditions combined with low humidity indicate a lack of the volatility required for tornado formation. Therefore, the collision of warm, moist air with cool, dry air is essential for the creation of the conditions needed to form tornadoes.