Headline, October 23 2022/ ''' '' MONSOON SCIENCE MOMENTS '' '''


 MOMENTS '' '''

SOUTH ASIA'S MONSOON IS BECOMING MORE and more extreme. From prolonged dry spells to relentless downpours, the consequences are growing and very dire.

Right across South Asia, climate change is making the monsoon more erratic, less dependable and even dangerous, with more violent rainfall as well as worsening dry spells.

For a region home to nearly one-quarter of the world's population, the consequences are destructive, dangerous and overwhelming.

In other parts of South Asia, the problem was too much rain, too quickly. Pakistan, to India's northwest, was struck by relentless downpours leaving much of the nation underwater and killing at least 1,500 people. In Bengaluru, India's tech capital, devastating rains in early September forced workers to use boats instead of cars in the streets.

MOISTURE-LADEN AIR BLOWING IN FROM THE ARABIAN SEA has nowhere to go but up. Hitting the Western Ghats it cools as it rises, the moisture condenses and falls as rain. 

THE MONSOON IS BECOMING more erratic because of a basic bit of science: Warmer air holds more moisture. The moisture accumulates in the atmosphere and can stay there longer, increasing the length of dry spells.

But then, when it does rain, ''it dumps all that moisture in a very short time,'' Dr. Koll said. ''It can be a month's rainfall or a week's rainfall in a few hours to a few days.

'A Palace For The Clouds' : In the 1870s, Sajjan Singh, the teenage ruler of the Mewar region in western India, ordered the construction of a marble palace on a rugged hill above lake city of Udaipur. The monsoon for him was a source of fascination, and the new palace would be a fine place to watch the clouds roll in.

Known as the Monsoon Palace, its eastern side offers a sweeping view of Udaipur and its glistening waters. But in summer the view from the opposite side is equally spectacular : the approach of moisture-laden monsoon clouds scudding across the sky. 

Those clouds are borne on winds from the southwest. And for a long time, that was most of what was known about the monsoon - it was caused by a shift in the winds that occurred in late spring and continued through summer.

At least as far back as the first century, sailors had learned to take advantage of these winds, riding them from the Middle East across the Indian Ocean and Arabian Sea to India.

OVER THE CENTURIES THE SUBCONTINENT has experienced weak or ''failed'' monsoons, in which the overall amount of rain is 20 percent to 30 percent lower than average.

A failed monsoon in 1899 led to the deaths of nine million people in central India, by some estimates.

In the middle of the 20th century, foreign aid helped India get through poor monsoons without famine. Since then, the improvements in agriculture have made a big difference.

IT WASN'T UNTIL THE 17TH CENTURY THAT Edmond Halley, the English astronomer and meteorologist best known for the comet that bears his name, finally described the monsoon's mechanism.

The shift in the winds - the arrival of rain - was caused by seasonal changes in the relationship between ocean and land temperatures.

He was right. And remarkably, ''His theory was entirely based on hearsay evidence,'' said Ranjan Kelkar, a student of the monsoon who headed the Meteorological Department from 1998 to 2003. ''Hally had never come to India.''

The British East India Company, which ruled the country for a century, until the mid-1880s. The company ''did many bad things, but among the good things was that it set up rain gauges and observatories."

A succession of British, and later Indian, scientists divined more details of the monsoon, including how the rains occur as the moist ocean air hits the subcontinent, rises and cools.

Scientists now know that the monsoon is quite complex. Other theories of how it originates have been developed, including one that ties the monsoon to the northwest shift of a zone of trade winds. But the basics, as Mr. Halley outlined, remain.An engine that drives it is the temperature difference between land and ocean.

In spring, as the Northern Hemisphere tilts towards the sun, the subcontinent heats faster than the ocean. As the air over the land warms, the air pressure drops, which draws in higher-pressure air from the ocean.

''That temperature difference creates this pressure difference that drives this moisture-laden air from the ocean toward the land,'' Dr. Koll said. The rotation of the earth gives these winds their direction.

But that's only part of the story, said Anders Levermann, a climate scientist at the Potsdam Institute for Climate Impact Research in Germany. ''The moment the first rain falls, the land gets cooled,'' he said.

THAT would be expected to stop, or at least slow, the monsoon by reducing the temperature difference  between land and ocean. But there's now another source of warmth over the land : the condensation of water vapor into droplets, which release heat. That maintains the temperature difference and keeps the monsoon going.

This self-sustaining feature is important. Dr. Levermann said, because it suggests that, as the world keeps getting warmer, year-to-year variability of the monsoon could increase. ''Once you have started the monsoon strong, it will become even stronger,'' he said. ''Once you have started the monsoon weak, it will become weaker.''

Dr. Rajendra Jenamani is a senior scientist with the national forecasting center at the India Meteorological Department in New Delhi. One of his jobs, in consultation with his colleagues, is to determine when the year's monsoon has actually begun.

For him, the arrival of the rains is less about how many weather stations have reported precipitation, and more about the senses and emotions. The abrupt shift in the wind. The sound of thunder, like a beating drum. The smell when the first raindrops hit the parched soil, kicking up dust.

''When the monsoons arrives, everything changes,'' he said.

The Honour and Serving of the Latest Global Operational Research and Writings on Monsoons, continues. The World Students Society thanks Henry Fountain, M.S. Amritha and N Krishna.

With respectful dedication to the Leaders of South Asian countries, and then Students, Professors and Teachers of the world. See Ya all prepare and register for Great Global Elections on The World Students Society - the exclusive ownership of  every student in the world : wssciw.blogspot.com and Twitter - !E-WOW! - The Ecosystem 2011 :

Good Night and God Bless

SAM Daily Times - the Voice of the Voiceless


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