How does air pressure typically change when rain is expected?

How does air pressure typically change when rain is expected?

• A. It rises
• B. It remains constant
• C. It falls
• D. It fluctuates unpredictably

Answer: (C)

When rain is expected, air pressure usually falls. This is because rain-bearing weather comes from a low-pressure system where air is rising. As warm air rises, the amount of weight pressing down at the surface decreases, so the atmospheric pressure measured at ground level drops. The falling pressure signals an approaching or intensifying storm that brings clouds and rain. If pressure rises, weather tends to improve; if it stays constant, conditions aren’t changing much. Fluctuations can occur, but the typical trend before or during rain is a decrease in pressure.

When rain is expected, air pressure usually falls. This is because rain-bearing weather comes from a low-pressure system where air is rising. As warm air rises, the amount of weight pressing down at the surface decreases, so the atmospheric pressure measured at ground level drops. The falling pressure signals an approaching or intensifying storm that brings clouds and rain. If pressure rises, weather tends to improve; if it stays constant, conditions aren’t changing much. Fluctuations can occur, but the typical trend before or during rain is a decrease in pressure.