The correct option is Influence of the Westerlies
Explanation
The global distribution of rainfall is primarily determined by the interaction between planetary wind systems and the location of landmasses and oceans. The direction from which prevailing winds blow dictates which side of a continent receives moisture-laden air first.Detailed Analysis:
- Role of Westerlies: Between the latitudes of 45° and 65° North and South, the dominant planetary winds are the Westerlies. These winds blow from the subtropical high-pressure belts towards the sub-polar low-pressure belts, moving generally from the west to the east.
- Moisture Transport: As the Westerlies travel across vast oceans in these latitudes, they pick up abundant moisture. When they reach the continents, they strike the western margins first. This results in heavy rainfall on the western coasts (e.g., British Columbia, Western Europe, Southern Chile).
- Comparison with Trade Winds: In contrast, the Trade Winds (0°-30° latitudes) blow from the east (Easterlies). Consequently, in the tropics, rainfall is typically heavier on the eastern margins of continents, while the western margins are often dry (leading to deserts).
Key Takeaway:
In the temperate zone (45°-65°), the Westerlies blow from west to east, causing the western margins of continents to receive precipitation first as the winds carry moisture from the oceans.