cyclone

The word 'cyclone' is one of the rare English words whose invention can be precisely attributed and dated.‍​‌​‍​‍​‌​‍​‍​‌​‍​‌​‍​‍​‌​‍​‌​‌​‌​‍​‌​‍​‌​‌​‍​‌​‍​‍​‌​‍​‌​‍​‍​‍ It was coined in 1848 by Henry Piddington, a British merchant mariner who served as president of the Marine Courts of Calcutta. Piddington coined the term in his 'Sailor's Horn-Book for the Law of Storms,' choosing the Greek word 'kýklos' (κύκλος, circle, wheel) as the base, to emphasize the circular, rotating nature of tropical storms in the Indian Ocean. He modeled the word on the pattern of other scientific terms derived from Greek.

The Greek 'kýklos' (circle) comes from PIE *kʷel- (to turn, to revolve), one of the most productive roots in the Indo-European family. Through Greek, this root gave English 'cycle' (a recurring sequence, literally a 'circle'), 'bicycle' (two wheels), 'tricycle,' 'encyclopedia' (literally 'all-around education,' from 'en' + 'kýklos' + 'paideía'), and 'cyclops' (literally 'round-eye' — the one-eyed giant). Through Latin 'colere' (to till, to cultivate — originally 'to turn the soil'), the same root produced 'culture,' 'colony,' 'cultivate,' 'agriculture,' and 'cult.' Through Germanic, it produced 'wheel' (Old English 'hwēol,' the thing that turns). Through Sanskrit, it produced 'chakra' (a spinning wheel or energy center). The idea of turning or revolving is the common thread binding this diverse word family.

Piddington's choice of the term was deliberate and practical. Sailors in the Indian Ocean needed a word for the devastating rotating storms that could destroy ships. The existing vocabulary was imprecise — 'storm,' 'tempest,' and 'hurricane' (a word from the Caribbean) did not capture the distinctive circular wind pattern. By the mid-nineteenth century, meteorologists had established that tropical storms rotated (counterclockwise in the Northern Hemisphere, clockwise in the Southern), and Piddington wanted a term that encoded this rotation.

In modern meteorological usage, 'cyclone' has several related but distinct meanings. In its broadest sense, a cyclone is any atmospheric system characterized by rapid inward circulation of air around a low-pressure center. By this definition, all hurricanes and typhoons are cyclones, and even mid-latitude weather systems (the familiar low-pressure areas on weather maps) are 'extratropical cyclones.' In common usage, however, 'cyclone' refers specifically to tropical cyclones in the Indian Ocean and South Pacific — the same phenomenon called a 'hurricane' in the Atlantic and eastern Pacific and a 'typhoon' in the western Pacific. The three words describe the same meteorological event; the distinction is purely geographic.

The Coriolis effect — the deflection of moving objects caused by the Earth's rotation — is responsible for the spinning motion that gives the cyclone its name and its etymology its aptness. In the Northern Hemisphere, air flowing toward a low-pressure center is deflected to the right, creating counterclockwise rotation. In the Southern Hemisphere, the deflection is to the left, creating clockwise rotation. At the equator, the Coriolis effect is zero, which is why tropical cyclones cannot form within about 5 degrees of the equator — there is not enough rotational force to start the spin.

The most devastating cyclone in recorded history was the Bhola Cyclone of 1970, which struck East Pakistan (now Bangladesh), killing an estimated 300,000–500,000 people. The catastrophe and the Pakistani government's inadequate response were contributing factors in the Bangladesh Liberation War of 1971.