What type of motion is produced by divergence near 300 mb?

• A. Rising motion with increasing surface pressure
• B. Falling motion with decreasing surface pressure
• C. Rising motion and falling surface pressure
• D. Neutral motion

Answer: (C)

Divergence at the 300 mb level refers to the outward flow of air at that altitude. When air diverges at this level, it leads to a reduction in the amount of air over a particular area, which causes the pressure at that altitude to decrease. As air moves away from a region, the remaining air tends to rise to fill the void, creating rising motion in the atmosphere.

This rising motion is associated with the development of low-pressure systems at the surface. As the air rises, it cools and may lead to cloud formation and precipitation, which are common characteristics of low-pressure areas. Consequently, as this rising motion occurs, the surface pressure in the vicinity decreases, consistent with the observed relationship between divergence at high altitudes and surface weather patterns.

In contrast, the other options do not accurately describe the effects of divergence at 300 mb. For example, rising motion accompanied by increasing surface pressure contradicts the fundamental relationship between rising air and low surface pressure. Moreover, neutral motion does not reflect the dynamics involved in divergence, as it neglects the critical effects on both vertical motion and pressure changes.