science

Icicle

Icicle is a 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 Icicle rather than just read about it. In short: An icicle is a spike of ice formed when water falling from an object freezes. Formation and dynamics Icicles can form during bright, sunny, but subfreezing weather, when ice or snow melted by sunlight or some other heat source (such as a poorly insulated building), refreezes as it drips off under exposed conditions.

Key takeaways

Icicle belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Icicle to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Icicle from memory before moving on to harder problems.

Reference excerpt

An icicle is a spike of ice formed when water falling from an object freezes.

Formation and dynamics Icicles can form during bright, sunny, but subfreezing weather, when ice or snow melted by sunlight or some other heat source (such as a poorly insulated building), refreezes as it drips off under exposed conditions. Over time continued water runoff will cause the icicle to grow. Another set of conditions is during ice storms, when rain falling in air slightly below freezing slowly accumulates as numerous small icicles hanging from twigs, leaves, wires, etc. Thirdly, icicles can form wherever water seeps out of or drips off vertical surfaces such as road cuts or cliffs. Under some conditions these can slowly form the "frozen waterfalls" favored by ice climbers. Icicles form on surfaces which might have a smooth and straight, or irregular shape, which in turn influences the shape of an icicle. Another influence is melting water, which might flow toward the icicle in a straight line or which might flow from several directions. Impurities in the water can lead to ripples on the surface of the icicles. Icicles elongate by the growth of ice as a tube into the pendant drop. The wall of this ice tube is about 0.1 mm (0.004 in) and the width 5 mm (0.2 in). As a result of this growth process, the interior of a growing icicle is liquid water. The growth of an icicle both in length and in width can be calculated and is a complicated function of air temperature, wind speed, and the water flux into the icicle. The growth rate in length typically varies with time, and can in ideal conditions be more than 1 cm (0.39 in) per minute. Given the right conditions, icicles may also form in caves (in which case they are also known as ice stalactites). They can also form within salty water (brine) sinking from sea ice. These so-called brinicles can kill sea urchins and starfish, which was observed by BBC film crews near Mount Erebus, Antarctica.

Dangers Icicles can pose personal and structural dangers. Icicles that hang from an object may fall and cause injury and/or damage to whoever or whatever is below them. In addition, ice deposits can be heavy. If enough icicles form on an object, such as a wire, beam, or pole, the weight of the ice can severely damage the structural integrity of the object and may cause the object to break. This can also happen with roofs, where failure can damage nearby parked vehicles or the contents and occupants of the structure. Icicles on roofs can also be associated with ice dams, which can cause water damage as the water penetrates below the shingles. The story of an English youth killed by a falling icicle in 1776 has often been recounted. Icicles are often used as weapons by children engaging in play, which can potentially lead to sharp force injury. A 2022 study showed that icicles could be used to penetrate most of the human body with enough depth to be able to compromise vital organs, with the practical exception of the chest region. Large icicles that form on cliffs near highways have been known to fall and damage motor vehicles. In 2010, five people were killed and 150 injured by icicles in Saint Petersburg, Russia after heavy snow that also caused apartment block roofs to collapse, as well as creating water damage to private homes and to the National Library of Russia.

Illustrations

Worked examples

Example 1 — a first encounter with Icicle

Start with the simplest possible case. Write down what Icicle claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In 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 Icicle 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 Icicle 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 Icicle

In research: Icicle appears in 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 Icicle 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: Icicle is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bodies of ice, Water ice, so understanding it makes those chapters shorter.
In everyday life: Look for Icicle 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 Icicle in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Icicle 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 Icicle out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Icicle in simple terms?

An icicle is a spike of ice formed when water falling from an object freezes. Formation and dynamics Icicles can form during bright, sunny, but subfreezing weather, when ice or snow melted by sunlight or some other heat source (such as a poorly insulated building), refreezes as it drips off under e…

Why does Icicle matter?

Because it connects several 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 Icicle?

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 Icicle.