Correct Option
The correct option isRising air cools down and condenses moisture.
Explanation
The relationship between atmospheric pressure and weather conditions is governed by the vertical movement of air. Low-pressure areas are regions of atmospheric instability characterized by the convergence of air at the surface and its subsequent upward movement (uplift).
Option Analysis
- Sinking air warms up and evaporates moisture. is Incorrect: Sinking air undergoes adiabatic compression, which causes it to warm up. Warmer air has a higher moisture-holding capacity, leading to the evaporation of clouds and clear skies. This process is characteristic of High-Pressure systems (anticyclones), not low-pressure areas.
- Rising air cools down and condenses moisture. is Correct: In a low-pressure system, surface air converges and is forced to rise. As the air rises, it expands due to decreasing atmospheric pressure aloft. This expansion leads to adiabatic cooling. When the air cools to its dew point, the water vapour condenses into liquid droplets or ice crystals, forming clouds and resulting in precipitation ("wet weather").
- High pressure pushes clouds away. is Incorrect: High-pressure systems are associated with diverging air that pushes outward and subsidence that inhibits cloud formation. While high pressure is associated with fair weather, this option does not explain the mechanism behind the wet weather of low-pressure systems.
- Winds blow from land to sea. is Incorrect: Winds blowing from land to sea are generally dry offshore winds (e.g., the retreating monsoon or land breeze). Wet weather is typically associated with onshore winds (sea to land) that bring moisture, but the fundamental cause of precipitation in a low-pressure zone is the vertical uplift and condensation, regardless of wind direction.
Key Takeaway
Low Pressure leads to rising air, adiabatic cooling, condensation, and precipitation (Bad Weather). High Pressure leads to sinking air, adiabatic warming, evaporation, and clear skies (Fair Weather).