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Saturday, Aug 17, 2019

Mumbaiwale: Fluid thoughts for a rainy day

Every time it rains, I’m filled with questions. Here are some answers…

mumbai Updated: Jun 14, 2019 21:59 IST
Rachel Lopez
Rachel Lopez
Hindustan Times
Picture for representation only.
Picture for representation only.(HT Photo)

What does ‘monsoon’ even mean?

At its core, it just means ‘season’. The English monsoon, in use since the 16th century (after British presence on the subcontinent necessitated a larger vocabulary for the unusual weather) comes from the Portuguese term monção. The Portuguese, in turn took the word from the Arabs. In Arabic, ‘mawsim’ means season, typically a wet and dry season, which explains the Urdu and Hindi ‘mausam’.

Why does India have such a robust monsoon anyway?

The popular version is easy to explain. Some 23 million years ago, a bit of land broke away from Africa and floated east towards the Asian landmass, shoving up against one side, forming the Indian subcontinent and pushing up land to form the Tibetan plateau and the Himalayas. This caused air pressures and temperatures to change, creating an annual spell of heavy rain in this part of the world.

Modern scientists believe it’s more complicated. A kind of early highland and mountains were already rising in Tibet, before the floating landmass crashed into Asia. And there were monsoon-like conditions across southern Asia much earlier. India’s east and east coasts get monsoon winds from the Arabian Sea and Bay of Bengal, and the Himalayas trap them within our region, so there’s no escaping the cloud party.

How did we figure this out?

Henry Blanford, India’s first meteorologist, made a key connection about 140 years ago. He noticed that in the years when there was less springtime snow cover on the Tibetan Plateau and Himalayan ranges, Indian’s rains in the following months would be heavier and more intense. He published his hypothesis in 1884, and hundreds of studies have since proved his theory.

So how come we still can’t predict the rains?

Because the monsoon has so many smaller influences and catalysts that even our most advanced ocean-atmosphere and wind models can’t keep up.

Monsoons don’t have the most consistent history. Scientists largely draw on two sources as archives of what’s been going on for millions of years. There are sediment cores from the Arabian Sea and stalagmites from caves in China. The sea core offers clues on what winds might have been like; the Chinese caves are more helpful to understand the East Asian Monsoon.

But last year, a team from the GEOMAR Helmholtz Centre for Ocean Research Kiel used samples from the Indian Ocean sea bed to study one million years of precipitation in the eastern Indian Ocean. They found that rains were weaker during the peak ice ages and strongest during warm periods like the present. Clearly we don’t know enough yet.

Is there a way to know more about the riot of green climbers, mosses and ferns that only flourish during this time?

Naturalist and fellow HT columnist Sunjoy Monga says that this monsoon undergrowth “makes up almost 50% of the region’s floral diversity” and has deep connections to the rest of the plant world. It certainly seems so – left unchecked, creepers cover everything, patches of land, tall trees, electric poles and entire mountainsides. Much of the Konkan looks like Sleeping Beauty’s kingdom while she slept. “Many of these species are what are called annuals,” Monga says. “They grow, flower and fruit and die in one growing season.” His favourite is the glory lily, an annual climber with spectacular radiating flowers that adds sparkle to the Mumbai wilds.

Bonus: What does the term cyclone mean?

Henry Piddington, a retired sea captain and president of the Marine Court of Calcutta, coined the term in 1840 to describe the circular, consistently changing, counterclockwise winds. He’d been studying why the Bay of Bengal was so tumultuous and thought that ‘cyclone’, derived from the Greek word ‘kyklon’, which means moving in a circle, like the coil of the snake, fit the phenomenon well.

First Published: Jun 14, 2019 21:58 IST

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