All questions of Climate for BPSC (Bihar) 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 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.

The term for the sudden onset of heavy rain during the monsoon season in India is "Monsoon Burst." This phenomenon is characterized by the rapid and heavy rainfall that marks the beginning of the monsoon season.

Western Coast and Western Ghats

The region of India that receives the highest amount of annual rainfall is the Western Coast and Western Ghats. This region is located along the western coastline of India, stretching from Gujarat in the north to Kerala in the south. The Western Ghats, a mountain range parallel to the coast, also plays a crucial role in influencing the rainfall in this region.

Monsoon Influence

The primary reason for the heavy rainfall in this region is the influence of the southwest monsoon winds. During the summer months, warm and moist air from the Arabian Sea is carried towards the Indian subcontinent by these monsoon winds. As this moisture-laden air encounters the Western Ghats, it is forced to rise, leading to the formation of clouds and subsequent rainfall.

Topography and Orographic Rainfall

The Western Ghats act as a barrier to the moisture-laden winds, causing them to rise and cool. As the air rises, it condenses and forms clouds, resulting in heavy rainfall along the windward side of the Western Ghats. This phenomenon is known as orographic rainfall. The Western Coast, being located on the windward side of the mountains, receives the maximum amount of rainfall.

Enhanced Rainfall

The Western Coast and Western Ghats also receive enhanced rainfall due to several factors:

1. Convergence of Winds: The coastal region experiences the convergence of the southwest and northeast monsoon winds, which further enhances the rainfall in this area.

2. Location and Orientation: The Western Coast and Western Ghats are situated in a way that they receive the maximum impact of the monsoon winds, resulting in higher rainfall.

Impact on Flora and Fauna

The high amount of rainfall in this region supports a diverse range of flora and fauna. The Western Ghats are recognized as a global biodiversity hotspot, with numerous endemic species of plants and animals. The heavy rainfall contributes to the growth of dense forests and the formation of numerous rivers and waterfalls.

In conclusion, the Western Coast and Western Ghats region of India receive the highest amount of annual rainfall due to the influence of the southwest monsoon winds, the presence of the Western Ghats mountain range, and the convergence of winds. This region's unique topography and location make it a vital contributor to India's overall rainfall patterns and support its rich biodiversity.

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.

Factors Influencing the Distribution of Annual Rainfall in India:
The primary factor that influences the distribution of annual rainfall in India is upper air circulation caused by global weather patterns.

Global Weather Patterns:
- The movement of air masses in the upper atmosphere, influenced by global weather patterns such as the Jet Stream and the Inter-Tropical Convergence Zone (ITCZ), plays a significant role in determining the distribution of rainfall in India.
- These weather patterns affect the direction and intensity of winds, which in turn influence the distribution of moisture-laden air and subsequent rainfall in different regions of the country.

Monsoon Winds:
- India's annual rainfall is largely dependent on the monsoon winds, which bring moist air from the Indian Ocean.
- The southwest monsoon winds, which bring the bulk of the rainfall to India, are influenced by the global weather patterns mentioned above.

Impact on Rainfall Distribution:
- The interaction of these upper air circulation patterns with local factors such as topography and proximity to water bodies determines the distribution of rainfall across different regions of India.
- Areas that are located in the path of moisture-laden winds receive higher rainfall, while regions shielded by mountain ranges may experience lower rainfall due to the rain shadow effect.

Conclusion:
In conclusion, while factors such as temperature variations and proximity to the Equator do play a role in influencing rainfall patterns in India, it is the upper air circulation caused by global weather patterns that serves as the primary factor determining the distribution of annual rainfall in the country.

Explanation:

Southern branch of the jet stream:
- The Southern branch of the jet stream is responsible for steering tropical depressions over India during the monsoon season.
- This branch of the jet stream flows over the southern part of India and plays a crucial role in the movement of weather systems, including tropical depressions.

Role in steering tropical depressions:
- During the monsoon season, tropical depressions form over the Bay of Bengal or the Arabian Sea.
- The Southern branch of the jet stream helps in directing these depressions towards India by influencing their track and movement.
- This branch of the jet stream can push the tropical depressions towards the Indian subcontinent, bringing heavy rainfall and influencing the overall monsoon pattern.

Impact on the monsoon season:
- The Southern branch of the jet stream is a key factor in determining the distribution of rainfall during the monsoon season in India.
- By steering tropical depressions towards the country, this jet stream branch contributes to the overall monsoon dynamics and influences the rainfall patterns across different regions of India.
- Understanding the role of the Southern branch of the jet stream is essential for predicting and analyzing the behavior of tropical depressions during the monsoon season in India.
Therefore, the Southern branch of the jet stream plays a significant role in steering tropical depressions over India during the monsoon season, impacting the country's rainfall patterns and overall weather conditions.

North Indian plain would have been much cooler in winter.

Factors influencing monsoon rainfall in India:

Western disturbances:
- Western disturbances are weather systems that originate in the Mediterranean region and move across Central Asia before reaching the Indian subcontinent.
- These disturbances bring moisture-laden winds and can interact with the monsoon winds, leading to increased rainfall in certain parts of India.
- The timing and intensity of western disturbances can significantly impact the monsoon rainfall pattern in the country.

Local wind patterns:
- Local wind patterns, such as sea breeze and land breeze, can affect the distribution of rainfall during the monsoon season.
- Sea breeze brings moist air from the sea, leading to increased rainfall in coastal areas, while land breeze carries dry air from land, resulting in less rainfall.
- The interaction of these wind patterns with the monsoon winds can influence the amount and intensity of rainfall in different regions of India.

Temperature variations:
- Temperature variations, both on a regional and global scale, play a crucial role in shaping the monsoon rainfall pattern.
- Warmer temperatures can lead to increased evaporation, which in turn can enhance the moisture content in the atmosphere, potentially leading to heavier rainfall.
- Temperature anomalies, such as El Niño or La Niña events, can also impact the monsoon circulation and influence the distribution of rainfall in India.
In conclusion, while all the factors mentioned above can influence the monsoon rainfall in India to some extent, western disturbances play a particularly significant role in determining the intensity and amount of rainfall during the monsoon season.

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 correct answer is option 'C', the north-eastern states of India receive the highest annual rainfall from the southwest monsoon. This region is known for its high precipitation levels and is often referred to as the "rainiest region" of India.

Reasons for the highest annual rainfall in the north-eastern states:

1. Geographic Location:
- The north-eastern states are located in the eastern part of India, bordered by the Himalayas in the north and Bangladesh in the south.
- This region is surrounded by hills and mountains, which act as barriers to the monsoon winds, causing them to rise and cool, leading to condensation and ultimately heavy rainfall.

2. Orographic Effect:
- The orographic effect plays a significant role in the high rainfall received by the north-eastern states.
- The monsoon winds, laden with moisture, are forced to rise as they encounter the Eastern Himalayas.
- As the air rises, it cools and condenses, resulting in the formation of clouds and subsequent rainfall.

3. Bay of Bengal Branch of Southwest Monsoon:
- The north-eastern states are primarily influenced by the Bay of Bengal branch of the southwest monsoon.
- Moisture-laden winds from the Bay of Bengal traverse over the region, leading to abundant rainfall.
- The Bay of Bengal is known for its warm sea surface temperatures, which provide the necessary moisture for the formation of rain clouds.

4. Relief Features:
- The relief features of the north-eastern states, characterized by hills, valleys, and plateaus, contribute to the rainfall pattern.
- The hills act as barriers, forcing the moist winds to rise and cool, which leads to enhanced precipitation.
- Additionally, the valleys and plateaus provide suitable conditions for the formation of clouds and rainfall.

5. Confluence of Wind Systems:
- The north-eastern states experience the convergence of multiple wind systems, namely the Bay of Bengal branch of the southwest monsoon, the south-westerly winds from the Arabian Sea, and the north-easterly winds from the Indian subcontinent.
- This convergence results in the upliftment of air masses, leading to the condensation of moisture and subsequent rainfall.

Therefore, due to its geographical location, orographic effect, influence of the Bay of Bengal branch of the southwest monsoon, relief features, and the confluence of wind systems, the north-eastern states of India receive the highest annual rainfall from the southwest monsoon.

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

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.

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.

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.

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.

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 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.

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 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 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.

The main cause of the variation in the distribution of annual rainfall in India is orographic effects and the presence of high mountains. When moist air is forced to ascend these mountains, it leads to variations in rainfall patterns across different regions of the country.

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.

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 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 season characterized by the retreat of the south-west monsoon in India is known as the "Retreating southwest monsoon season," which occurs from October to November.