Monsoon - GS questions based on daily current affairs

ANSWER: Aerosol interaction with rainfall

Explanation:

• The project “South West Asian Aerosol - Monsoon Interactions (SWAAMI)”, involves measurements of aerosols across northern India and the Bay of Bengal during the pre-monsoon which will then be synthesized with long term measurements from ground based networks and data from previous intensive campaigns.
• The study is expected to characterize the mechanisms by which aerosols influence the Indian monsoon.
• This joint effort is part of the implementation agreement signed between MoES and Natural Environment Research Council (NERC), UK on “Predicting the Variability of the South Asian Monsoon” under the existing MoU between MoES and UK on Collaboration in Earth System Science. Three research projects involving the Indian and UK scientists will study different aspects of physical processes affecting the monsoon.

ANSWER: Monsoon bursts suddenly

Explanation:

• Southwest monsoon hits the Kerala coast every year precisely on June 1. Monsoon does not come gradually; it “bursts” suddenly on a single day.
• Sub-Tropical Jet stream (STJ) is a narrow band of fast moving air flowing from west to east [Westerlies]. This jet stream is bifurcated by the Himalayan ranges and Tibetan Plateau.
• A warm-core anticyclone is formed over this plateau during the summer monsoon period. It is the result of a process called anticyclogenesis.
• At the beginning of June, the STJ disappears from the southern side of the plateau. In other words, the jet disappears completely over northern India accentuated by the anticyclogenesis created by the Tibetan plateau. This sudden shift is the cause of the “bursting” of the monsoon.
• Easterly winds blow in the mid-troposphere and are known as the Tropical Easterly Jet. This jet extends far to the south of Tibet and the air flow is roughly along the Calcutta-Bangalore axis.

ANSWER: Anticyclone

Explanation:

• The summertime heating of the plateau of Tibet is the most important factor in the causation and maintenance of monsoonal circulation.
• The Tibet Plateau is 600 kilometers wide in the west and 1,000 kilometers wide in the east. Its length is about 2,000 km. The average height of the plateau is about 4,000 meters. Thus, it is an enormous block of high ground acting as a formidable barrier. The summer-time heating of Tibetan Plateau makes it a heat source.
• A warm-core anticyclone is formed over this plateau during the summer monsoon period. It is the result of a process called anticyclogenesis.

ANSWER: Increases albedo effect of land over ocean

Explanation:

• An important contributor to monsoon weakening is the albedo effect of deforestation by humans.
• Reduced land cover increases the reflectivity (albedo effect) which leads to cooling of land in contrast to the ocean and results in a weakened monsoon circulation.

ANSWER: They reduce incoming solar radiation

Explanation:

• Anthropogenic atmospheric aerosols, including sulphates, black carbon, nitrates and dust accumulate over the Indo-gangetic plains. These reduce incoming solar radiation over northern India and the northern Indian Ocean and lead to cooling on both land and sea resulting in a lowered thermal contrast.
• Hence, monsoon winds and circulation are weakened as both land and sea are cooled. Evaporation is also suppressed. Over South Asia, over 50 per cent of aerosol emissions are caused by biomass and agricultural burning. There is mounting evidence of the emissions from South Asia and China in changing the timing, spatial distribution and strength of the monsoon.
• However, negative impacts of these aerosols can be reduced quickly as they have a short lifetime of few weeks compared to GHGs which can stay in the atmosphere for up to 80 years.

ANSWER: Assertion & Reason both are correct and Reason is the correct explanation.

Explanation:
The Arabian sea is larger than bay of bengal so more moisture is picked up by the monsoonal winds while passing over it.

ANSWER: Western Disturbances

Explanation:
Western Disturbances originate in the Mediterranean sea and Atlantic ocean. These winds move towards the East bringing Cyclonic rain in temperate zone.

ANSWER: Both

Explanation:
No explanation is available for this question!