earth science

Nor'westers

Nor'westers is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Nor'westers rather than just read about it. In short: The Nor'westers are a localised rainfall and thunderstorm event which occurs in the region of Eastern South Asia. This includes the region of Bengal (Bangladesh and West Bengal) and the regions of Odisha, Tripura, Assam, Bihar, Jharkhand in East India and Northeast India and the adjacent regions of Nepal during the summer months.

Key takeaways

Nor'westers belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Nor'westers to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Nor'westers from memory before moving on to harder problems.

Reference excerpt

The Nor'westers are a localised rainfall and thunderstorm event which occurs in the region of Eastern South Asia. This includes the region of Bengal (Bangladesh and West Bengal) and the regions of Odisha, Tripura, Assam, Bihar, Jharkhand in East India and Northeast India and the adjacent regions of Nepal during the summer months. These storms generally occur in the afternoon or just before sunset, when thick dark black clouds start appearing over the sky and then bring gale-speed wind with torrential rain, often with hail, but spanning only a short period of time.

Etymology They are also known as kalboisakhi or kalbaisakhi (Bengali: কালবৈশাখী, romanized: Kālbôiśākhī, pronounced [kaːlboiʃakʰi]; Odia: କାଳ ବୈଶାଖୀ, romanized: Kāḷa Baiśākhī, pronounced [kaɭɔ̟ bɔ̟isakʰi]), and as bordoisila (Assamese: বৰদৈচিলা, romanized: Bôrdôisilā, pronounced [bɔ̞ɹdo̞isilä]). In these languages, the term kālbôiśākhī refers to a "fateful thing" which occurs in the Hindu month of Baishakh. The term nor'wester is more commonly used in English newspapers since these storms travel from northwest to southeast. In Assamese, the event is known as a bôrdôisilā, which is derived from the Bodo word bôrdôisikhlā, in which bôr means wind, dôi means water and sikhlā means girl, represents the goddess of nature, wind and rain and also marks the beginning of the Assamese month Bôhāg or Baishagu.

Genesis

The period of kalboisakhi formation generally begins in April and lasts until the monsoon establishes itself over Northeast India, although March kalboisakhi are not unknown. Based on event descriptions and the meteorological environments involved, these storms can be classified as progressive derechos. kalboisakhi originate over the Chhotanagpur Plateau between the states of Bihar and Jharkhand. They gradually gain strength as they move southeastwards and impact the states of Odisha, West Bengal, and Assam with gale-speed winds (often exceeding 100 km/h (62 mph)), torrential rains, and hailstorms. On some occasions, incursion of moist air in these elevated places, when combined with high surface temperatures, causes violent thunderstorms. Tornadoes also rarely form if there is enough moisture, convection and heat in the Ganges-Brahmaputra Delta; one such tornado killed over a thousand people when it struck Bangladesh in 1989, making it the deadliest tornado in history.

Effects Kalboisakhi brings destruction by uprooting trees due to gale winds and waterlogging roads due to heavy rainfall. It often damages crop by hailstorms. However it is extremely helpful for kharif crops like jute, paddy, etc. and give relief after the mid-day heat and give rainfall to the dry soils for the development of the crops. Due to global warming, these storms are becoming infrequent and becoming stronger, causing more destruction.

In Bengali literature Many Bengali poets and artists have regarded "kalboisakhi" as events of astounding beauty. Bengali poet Mohit Lal Majumder described the storm in his poem Kalboisakhi, and the storms also inspired Rabindranath Tagore's poem Esho Hey Boisakh (lit. 'Come, oh Boisakh').

Photography

Illustrations

Worked examples

Example 1 — a first encounter with Nor'westers

Start with the simplest possible case. Write down what Nor'westers claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Nor'westers before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Nor'westers ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Nor'westers

In research: Nor'westers appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Nor'westers in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Nor'westers is common in secondary-school and first-year university syllabi. It links to neighbouring topics Climate of Asia, Weather events in Bangladesh, Weather events in India, so understanding it makes those chapters shorter.
In everyday life: Look for Nor'westers outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Nor'westers in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Nor'westers means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Nor'westers out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Nor'westers in simple terms?

Why does Nor'westers matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Nor'westers?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Nor'westers.