Coastal & maritime basics — wind and extreme air motion phenomena Choose the most accurate comprehensive statement about wind-driven effects and extreme rotating air columns in the marine environment.

Introduction / Context:
Marine and coastal structures experience environmental loads from wind, waves, and, in rare cases, severe rotating storms. Basic awareness of how wind interacts with the sea surface and structures is essential for conceptual design and risk assessment.

Given Data / Assumptions:

• Wind can both directly load a structure and indirectly generate waves.
• Vortex formation over water can create surface depressions.
• Severe rotating air columns (tornadoes/waterspouts) can occur over or near water.

Concept / Approach:

Design guidance requires considering wind pressures and the waves they induce. Vortical structures in the atmosphere may couple to the water surface, creating observable conical depressions. Tornadoes (and waterspouts over water) are intense rotating columns with high tangential velocities that pose extreme hazards to navigation and infrastructure.

Step-by-Step Solution:

Verification / Alternative check:

Codes and coastal manuals list wind and waves as governing environmental actions. Observations of waterspouts/tornadoes show conical surface depressions, validating options (a)–(c).

Why Other Options Are Wrong:

• “None of the above” contradicts well-established physical behavior and design practice.

Common Pitfalls:

• Separating design for wind and waves; in reality, they are coupled.
• Ignoring extreme but low-probability events in risk assessments.

Final Answer:

All of the above.