All questions of Climate for UPSC CSE Exam

• During the hot weather period i.e from March to May the Eastern and North-eastern states of the subcontinent like West Bengal, Bihar, Assam, Odisha (parts) and Bangladesh experience a dramatic appearance of a special type of violent thunderstorm known as Nor’wester.
• In Bengal it is known as ‘Kal Baisakhi’ Apart from its destructive effects like a sudden rise in wind speed, lightning, thunder and hail the rainfall associated with the storm although small in amount, is extremely helpful for the pre-Kharif crops like jute, paddy, summer till and a large number of vegetables and fruits and the sudden drop in temperature gives relief after unbearable midday heat.

The north-eastern states of India receive the highest annual rainfall from the southwest monsoon. This is due to their hilly terrain and proximity to the Bay of Bengal, which results in heavy rainfall in this region.

The Intertropical Convergence Zone (ITCZ), known by sailors as the doldrums, is the area encircling the earth near the equator where the northeast and southeast trade winds converge.

Retreat of the South-West Monsoon
The retreat of the south-west monsoon marks a significant climatic transition in India. This season typically occurs from mid-September to November and is characterized by several distinct features.
Characteristics of the Retreating Monsoon
- Decreasing Rainfall: As the monsoon winds start to retreat, the intensity and frequency of rainfall diminish. The heavy downpours of the monsoon give way to sporadic showers.
- Change in Temperature: With the withdrawal of the monsoon, temperatures begin to rise after the cooler monsoon months. This period often experiences warm days and cooler nights.
- Formation of Cyclones: The retreating monsoon season is also known for the formation of tropical cyclones in the Bay of Bengal. These can lead to significant weather events, sometimes causing heavy rainfall in coastal regions.
- Agricultural Impact: Farmers rely on the retreating monsoon for the timely harvest of kharif crops. The weather patterns during this time are crucial for the agricultural cycle.
Conclusion
In summary, the retreating south-west monsoon season is a critical period in India's climate calendar. It signifies the end of the monsoon rains and sets the stage for the transition to the cooler months ahead. Understanding this season is essential for agricultural planning and disaster preparedness in response to possible cyclonic activity.

The western coast of India, along with the Western Ghats, receives the highest amount of annual rainfall in the country. This region is known for its heavy and consistent rainfall.

Understanding Rainfall Variation in India
The variation in the distribution of annual rainfall in India is primarily influenced by orographic effects and the presence of high mountains.
Orographic Effects
- Orographic effects refer to the changes in atmospheric conditions caused by the presence of mountains.
- In India, the Himalayas play a crucial role in determining rainfall patterns.
Role of the Himalayas
- The Himalayas act as a barrier to the southwest monsoon winds, forcing them to rise.
- As air rises, it cools and condenses, resulting in precipitation. Areas on the windward side of the mountains receive heavy rainfall, while the leeward side (rain shadow region) experiences significantly less rainfall.
Monsoon Patterns
- The Indian monsoon is heavily influenced by orographic features.
- Regions like the Western Ghats and northeastern states see substantial rainfall due to the orographic lift.
Impact on Climate Zones
- This variation leads to distinct climate zones across India, from the lush forests of the Western Ghats to the arid deserts of Rajasthan.
- Thus, orographic effects shape the agricultural practices and water availability in different regions.
Conclusion
The presence of high mountains significantly contributes to the variation in annual rainfall distribution in India, making option 'C' the correct answer. Understanding these geographical features is vital for comprehending the complex climatic patterns of the country.

The primary source of moisture for the south-west monsoon winds in India is the Indian Ocean. These winds carry moisture from the Indian Ocean and bring it to the Indian subcontinent, leading to rainfall.

North Indian plain would have been much cooler in winter.

In northern India, there is light rainfall during winter. This is caused by the cyclonic storms which originate in the Mediterranean Sea and travel towards India. These winds are called western disturbances. They cause heavy snowfall in the higher reaches of the Himalayas and rainfall in the plains. They result in a cold wave in northern India.

India is located in the middle of the tropic of cancer.

The southern branch of the jet stream is responsible for steering tropical depressions over India during the monsoon season. These depressions play a significant role in the distribution of monsoon rainfall.

Monsoon season in India is characterized by heavy rainfall, which is vital for the country's agriculture and overall water supply. During this season, there are certain weather phenomena that occur, one of which is the sudden onset of heavy rain. This occurrence is commonly referred to as the "Monsoon Burst."

Explanation:
- The monsoon season in India typically begins in June and lasts until September. During this period, warm and moist air from the Indian Ocean moves towards the Indian subcontinent, bringing rainfall.
- The onset of the monsoon season is usually gradual, with light rainfall in the beginning. However, there are instances when there is a sudden and intense increase in rainfall, which is known as the "Monsoon Burst."
- The Monsoon Burst is characterized by a heavy downpour that occurs over a short period, usually within a few hours. This sudden onset of heavy rain can lead to flooding, waterlogging, and other related issues.
- The Monsoon Burst is a result of various factors, including the interaction between the southwest monsoon winds and local weather conditions. The southwest monsoon winds bring moisture-laden air, which converges with other weather systems such as low-pressure areas, troughs, and cyclones.
- When these weather systems interact with the monsoon winds, they trigger an intense release of moisture, leading to heavy rainfall. This sudden burst of rain is often accompanied by strong winds and thunderstorms.
- The Monsoon Burst is crucial for the overall monsoon rainfall in India. It helps in maintaining the water balance and replenishing reservoirs, rivers, and groundwater sources.
- However, the intensity of the Monsoon Burst can sometimes lead to problems like flash floods, landslides, and disruption in daily life. Therefore, it is important for the authorities to be prepared and take necessary measures to mitigate the impact of such heavy rainfall events.
- Overall, the Monsoon Burst is a significant weather phenomenon during the monsoon season in India, bringing sudden heavy rains that are both beneficial and challenging for the country's agricultural and water systems.

The main reason for the variation in rainfall received by different regions of India during the monsoon season is the presence of high mountains and orography. When moist air is forced to ascend the slopes of mountain ranges or the edge of plateaus, it cools down, gets saturated, and leads to heavy rainfall on windward slopes. This creates variations in rainfall patterns across the country.

Understanding the South-West Monsoon in India
The south-west monsoon is a significant climatic phenomenon in India, marking a transition from the hot and dry conditions of pre-monsoon months to a season characterized by heavy rainfall.
Characteristics of the Hot-Wet Season
- Timing: The hot-wet season typically begins in June and lasts until September.
- Rainfall: This period is characterized by intense rainfall due to the south-west monsoon winds that bring moisture-laden air from the Arabian Sea and the Bay of Bengal.
- Temperature: Although the season starts with high temperatures, the onset of rain significantly cools the atmosphere, providing relief from the heat.
Impact on Agriculture
- Crop Growth: The arrival of the monsoon is crucial for agriculture in India, as it provides the necessary moisture for Kharif crops such as rice, maize, and pulses.
- Water Resources: The monsoon replenishes rivers, lakes, and groundwater, ensuring a sustainable water supply for irrigation and drinking purposes.
Regional Variations
- Geographical Influence: The intensity and timing of the monsoon vary across different regions. Coastal areas and the Western Ghats receive heavy rainfall, while some interior regions may experience less precipitation.
Conclusion
In summary, the hot-wet season is a critical period marked by the onset of the south-west monsoon, which brings substantial rainfall vital for the agricultural landscape of India. Understanding this season is essential for grasping India's climatic patterns and agricultural dependencies.

The distribution of annual rainfall in India is primarily influenced by upper air circulation caused by factors controlling global weather patterns. This includes the presence of jet streams and the movement of air masses at higher altitudes, which play a crucial role in determining India's weather and monsoon patterns.

High and dry winds would blow outwards from this high-pressure area when high pressure develops over the North-Western part of India.

Pune is on the leeward side of the Western Ghats, it means that it lies in a rain shadow area. But Mumbai lies on the windward side and receives heavy rainfall. Vidarbha region experiences a semi-arid climate as it is located in a rain shadow region.

The rainshadow effect in certain regions of India is caused by the presence of high mountains and orographic effects. When moist air is forced to ascend these mountains, it leads to heavy rainfall on windward slopes and creates a rainshadow region on the leeward side with much lower rainfall.

The onset of the south-west monsoon in India is crucially determined by the movement of the ITCZ (Inter-Tropical Convergence Zone). As this zone shifts northward, it attracts the south-west monsoon winds towards the Indian subcontinent.

Western disturbances are low-pressure systems that originate in the west Asian and Mediterranean regions and affect India during the winter season, bringing rainfall to certain regions.

Monsoon rains are crucial for Indian agriculture, and approximately 80% of agriculture in India depends on these rains. This heavy reliance on monsoons highlights their significance for the country's agricultural sector.

The distribution of rainfall during the winter months in India is primarily influenced by the frequency of western disturbances. These disturbances, originating in regions like the Mediterranean Sea, bring rainfall to northern India during the winter season.

The pulsating nature of the monsoon in India, with wet and dry spells, is primarily influenced by the movement of the monsoon trough of low pressure. The position of this trough and its axis determines the intensity and distribution of rainfall. When it shifts, it can result in longer dry spells or widespread rains.

The Arabian Sea branch of the southwest monsoon brings rainfall to the west coast of India, including states like Kerala and Karnataka. This branch of the monsoon is responsible for the heavy rainfall in these coastal areas.

The Himalayan region, including Jammu and Kashmir and Himachal Pradesh, experiences the coldest temperatures in India, with temperatures often falling below freezing point during winter.

The northern plains of India, particularly Rajasthan, experience some of the highest temperatures in the country, with summer temperatures often reaching up to 50?C. This is due to factors like inland location and hot, dry winds.