Thunderstorms are typically caused by which of the following processes?

Thunderstorms are primarily caused by the upward movement of warm, moist air. This process, known as convection, occurs when the surface temperature rises, especially on warm, humid days. As the air at the surface heats up, it becomes less dense and begins to rise. When this warm, moist air ascends, it cools at higher altitudes, causing the water vapor in the air to condense into clouds. As condensation occurs, it releases latent heat, which further fuels the upward motion of air, leading to the development of powerful cumulonimbus clouds associated with thunderstorms.

The presence of warm, moist air is essential for the formation of thunderstorms because it provides the necessary energy and moisture for cloud formation and precipitation. This process explains why they tend to occur in areas with high humidity and warmth, particularly in tropical and temperate climates.

In contrast, the other options are not conducive to the formation of thunderstorms, as they either involve cooler air that does not support convection or refer to atmospheric conditions that inhibit storm development. High-pressure systems typically lead to stable and clear conditions, while the absence of cloud formations indicates that there is insufficient moisture or upward motion in the atmosphere to generate thunderstorms.