Obstruction of moisture-laden winds by the windward slope
Explanation
The heavy precipitation in the Western Ghats is a classic example of Orographic Rainfall (or Relief Rainfall). This phenomenon occurs when moisture-laden air is forced to ascend a physical barrier, such as a mountain range, leading to adiabatic cooling, condensation, and precipitation.
Detailed Analysis:
- Location in the path of the Arabian Sea branch is incorrect as the primary reason: While the location places the region in the path of the Arabian Sea branch of the South-West Monsoon, location alone does not guarantee heavy rainfall. For example, the Aravalli Range runs parallel to the wind direction, resulting in minimal rainfall despite being in the path of the winds. The obstruction is the critical factor.
- Obstruction of moisture-laden winds by the windward slope is Correct: The Western Ghats act as a continuous barrier perpendicular to the moisture-laden South-West Monsoon winds. The windward slopes obstruct the airflow, forcing it to rise. As the air rises, it cools and condenses, causing heavy rainfall on the western slopes.
- Presence of frequent tropical depressions is incorrect: Tropical depressions are more characteristic of the Bay of Bengal branch or the retreating monsoon season. While they influence Indian weather, the consistent heavy rainfall in the Ghats is primarily due to the steady monsoon flow interacting with the topography, not frequent depressions.
- High altitude of the Deccan Plateau is incorrect: The altitude of the Deccan Plateau is relevant to the leeward side (rain shadow region). The heavy rainfall occurs on the windward side (Ghats), while the plateau receives significantly less rain because the air descends and warms up after crossing the summit.
Key Takeaway:
The Western Ghats receive heavy rainfall primarily due to the orographic effect, where the steep windward slopes obstruct the Arabian Sea branch of the South-West Monsoon, forcing the moist air to rise and precipitate.