Ans: A

Exp:

Since 1954, the state of Assam has withstood many devastating floods; on average, Assam receives three to four waves of floods every year between May to September. These floods occur due to overflow from downpours and high sediment levels from landslides. Deforestation and shifting cultivation add to the woes.

The River Brahmaputra receives a number of tributaries throughout its 750 km long journey through the Assam valley. The rivers Burhi Dihing and Dhansari form the left bank tributaries, whereas Subansiri, Kameng, Manas and Sankosh form the right bank tributaries. The flood discharge of the Brahmaputra River is one of the highest in the world. As for annual sediment transport, it reaches approx. 500 million tons, and is the second-highest, next to the Yellow River in the People’s Republic of China. Thus, the River Brahmaputra is partially responsible for the floods in Assam.

Ans: B

Exp:

Statement 1 is incorrect: During the phase of the southwest monsoon, there are also periods where, after having rain for a few days, the rain fails to occur for one or more weeks in most parts of India; this phenomenon is called a break in the monsoon.  These dry spells are quite common during the rainy season. It is not associated with the retreating monsoon. Also, over the west coast, the dry spells are associated with days when winds blow parallel to the coast.

Statement 2 is incorrect: Blossom showers are pre-monsoon showers in the state of Kerala. When these showers arrive, the coffee flowers blossom in Kerala and nearby areas.

Statement 3 is correct: Monsoon breaks are caused by shifting of monsoon trough (area of low pressure). This low-pressure zone inches close to the Himalayas during the arrival of the monsoon. The rainfall breaks or stops in the northern region when this trough is in alignment with the Himalayas and shifts completely northward. This results in a complete pause in rainfall for a few weeks over the northern plains. 

Ans: C

Exp:

The winter monsoons move from land to sea, and they do not cause rainfall. This is due to the fact that 

• The winter monsoon has very little humidity.
• The presence of anti-cyclonic circulation on land reduces the possibility of rain.

  So, most parts of India do not have rainfall in the winter season. However, there are some exceptions: 

• North-West India and the states of Delhi, UP, Punjab, and Haryana receive winter rainfall from temperate cyclones originating from the Mediterranean Sea, known as a western disturbance. The rainfall average in Delhi is around 53 mm. 
• In Punjab and Bihar, rainfall remains between 25 mm and 18 mm, respectively.
• Winter rainfall occasionally visits the Central parts of India and the northern parts of the southern Peninsula.
• The states of Arunachal Pradesh and Assam in the northeastern parts of India also have rainfall between 25 mm and 50 mm during these winter months.
• In the winter months, the northeast monsoon crosses over the Bay of Bengal and picks up moisture, which results in torrential rainfall over the Tamil Nadu coast,  southern Andhra Pradesh, southeast Karnataka, and southeast Kerala.

Ans: C

Exp :

Option (a) is incorrect: The Western cyclonic disturbance, which enters India during the winter months from the North West part of India, is generally accompanied by an increase in prevailing night temperatures. A marked increase in the prevailing night temperature generally indicates an advance in the arrival of these cyclone disturbances.

Option (b) is incorrect: The easterly jet streams are a phenomenon of the summer and monsoon months; they bring tropical depressions into India.  These tropical depressions have a very important role in the distribution of monsoon rainfall throughout the Indian subcontinent

Option (c) is correct: The easterly Jet streams have a very important role to play in the Indian monsoon, and their advent is characterised by a very high intensity of rainfall. Most of the North East and Eastern parts of India receive heavy rainfall due to easterly Jet streams.

Option (d) is incorrect: The Tropical easterly Jet (TEJ) stream is generally located around 14° N latitude during the summer months. The jet stream runs from the east coast of Vietnam to the west coast of Africa. Normally, the jet is at an accelerating stage from the South China Sea to South India and decelerates thereafter. The location of the Easterly Jetstream seems to influence the pattern of monsoon rainfall. TEJ weakens to less than 50 knots over India in September. During Break monsoon conditions, TEJ moves northward up to latitude 20ºN.

Ans: A

Exp:

El Niño and La Niña are atmospheric patterns that influence the warming and cooling of sea surface temperatures in the Central and Equatorial Pacific.  The two opposing patterns occur in an irregular cycle called the El Niño Southern Oscillation (ENSO) cycle. This phenomenon was discovered by Sir Gilbert Walker.

Statement 1 is incorrect : In El Nino year, the following phenomenon occurs:

• • El Niño is the warming of sea waters in the Central-east Equatorial Pacific that occurs every few years. During El Niño, surface temperatures in the equatorial Pacific rise, and trade winds — east-west winds,  that blow near the Equator weaken.

• During El Nino, the colder waters near the Peruvian coast gets warm and experience low-pressure situation.

• Normally, easterly trade winds blow from the Americas towards Asia. Due to El Niño , they falter and change direction to turn into westerlies, bringing warm water from the western Pacific towards the USA.

Statement 2 is correct : El Nino is an extension of the warm equatorial current, and during the phenomenon, the warm equatorial current is replaced temporarily by cold Humboldt or Peruvian current.  This results in the rise in the temperature of water along the coast of Peru by around 10°C.  This results in:

• Distortion of equatorial atmospheric circulation;

• Irregularities in the evaporation of seawater; 

• Reduction in the amount of planktons which further reduces the number of fish in the sea.

Further, when there is a transition from a La Niña winter – to a season of summer affected by EL Nino, it has historically tended to produce the largest deficit in the monsoon as, the pre-monsoon as well as monsoon circulations tend to be weaker in an El Niño year.