In Indian climatology, why does the west coast of India receive much more rainfall from the southwest monsoon than the east coast?

Introduction / Context:
The Indian monsoon system is controlled by the interaction of moist winds with relief features such as mountain ranges. One of the striking patterns is the very high rainfall along the western coast of India during the southwest monsoon, contrasted with relatively lower rainfall on parts of the east coast. This question tests your understanding of how the Western Ghats influence monsoon winds and create orographic rainfall.

Given Data / Assumptions:

• The season in focus is the southwest monsoon, which blows from the Arabian Sea and Bay of Bengal.
• We compare rainfall on the west coast versus the east coast of India.
• Options mention coastal shape and orientation of the Western and Eastern Ghats.
• We assume the standard direction of the southwest monsoon winds from June to September.

Concept / Approach:
When moisture laden winds meet a mountain barrier, they are forced to rise, cool, and condense, leading to orographic rainfall on the windward side. The Western Ghats run almost parallel to the west coast and form a steep barrier quite close to the Arabian Sea. The southwest monsoon winds from the Arabian Sea strike these hills directly, giving heavy rainfall on the windward slopes and coastal plains, while the leeward rain shadow region inland receives much less rain. In contrast, the Eastern Ghats are lower and more discontinuous, so they do not block the monsoon in the same way.

Step-by-Step Solution:
Step 1: Recognise that the southwest monsoon winds from the Arabian Sea blow roughly from the southwest toward the northeast. Step 2: The Western Ghats lie close and almost parallel to the west coast, presenting a continuous high barrier to these winds. Step 3: When the moist winds hit the Western Ghats, they are forced to rise, cool, and drop most of their moisture as heavy rainfall on the western side. Step 4: By the time these winds cross the Ghats and descend toward the Deccan interior, much of the moisture has already been released, reducing rainfall inland and on the lee side. Step 5: The east coast, influenced mainly by Bay of Bengal branch winds, does receive rain but does not have a similarly high continuous barrier so close to the sea. Step 6: Therefore, the presence of the Western Ghats as an orographic barrier is the main reason the west coast gets heavier southwest monsoon rainfall.

Verification / Alternative check:
You can verify this reasoning by looking at rainfall maps of India. Cities along the west coast such as Mumbai, Mangaluru, and Kochi record very high annual rainfall, whereas some locations in the rain shadow region of the Deccan plateau, not far inland, receive much less. The pattern closely follows the line of the Western Ghats. This spatial evidence supports the orographic explanation and confirms option B as the correct one.

Why Other Options Are Wrong:
The idea that the west coast is simply straight does not adequately explain the rainfall difference because coastline shape alone does not guarantee heavy precipitation. The suggestion that the east coast being broader reduces rainfall is vague and not supported by climatology. The statement about the Eastern Ghats extending parallel to the wind direction is partially true for some stretches but does not explain why the west coast, not the east, receives the heaviest early monsoon showers. Only the explanation involving the Western Ghats acting as a barrier correctly captures the main mechanism.

Common Pitfalls:
Students sometimes focus on minor geographic features such as coastal indentation or simple distance from the sea without considering the crucial role of relief. Another common mistake is to forget that the Arabian Sea branch of the monsoon hits the Western Ghats almost head on, while the Eastern Ghats are lower and broken, allowing winds to pass more easily. Always relate rainfall distribution to topography when analysing such questions.

Final Answer:
The west coast of India receives more rainfall from the southwest monsoon mainly because the Western Ghats obstruct the moist winds and cause heavy orographic rainfall.