A low pressure system is defined as?

• A. A large body of circulating air with low pressure at its center and higher pressure outside of the system.
• B. A region where air rises and pressure is high at the center.
• C. A layer of air with stable temperature and no movement.
• D. A system associated with dry, clear conditions with gentle breezes.

Answer: (D)

A low pressure system is a region where the center of the atmosphere has lower pressure than the surrounding air, causing air to flow toward the center from all directions. As air converges at the surface and rises, it cools and condenses, forming clouds and often bringing雨 or storms. This rising motion gives low pressure systems their characteristic unsettled weather. In contrast, dry, clear conditions with gentle breezes come from descending air in a high pressure system, which suppresses cloud formation. So the defining idea is a lower-pressure center with air rising and weather that tends to be cloudier and more active, not clear and calm.