IELTS Academic Reading Practice Test 80

Before the eighteenth century, a sudden thunderstorm could be far more destructive than it is today. Lightning regularly set fire to tall structures such as church spires, castles and windmills, and because most buildings contained large amounts of timber, a single strike could reduce a barn or a ship to ashes within minutes. Coastal towns were particularly vulnerable, as wooden vessels in harbour could be destroyed before crews had time to react. Many people interpreted these disasters as expressions of divine anger, and there was no agreed way to protect property from them. Scientific understanding of electricity grew only gradually, but during the 1700s it began to offer practical answers to an ancient danger.

One of the central figures in this story was Benjamin Franklin, a printer and statesman from Philadelphia, who developed a strong interest in electricity in the 1740s. After observing that the sparks produced by laboratory machines shared many properties with lightning, Franklin argued that storm clouds carry an electrical charge and that lightning is simply a very large electrical discharge or spark.

In 1749 he suggested that a tall metal rod fixed to the top of a building could draw electrical fire from a cloud before it could strike, provided that the rod was connected to the earth by a wire. Franklin described this proposal in letters to European scientists and later in his influential book Experiments and Observations on Electricity, published in 1751.

To prove that lightning was electrical, Franklin devised his famous experiment with a kite. In June 1752 he flew a kite during a thunderstorm, with a small key attached to the string, and observed that the key gave off sparks when he brought his knuckle close to it. The experiment confirmed that storm clouds carry electricity, and it helped to persuade both scientists and the public that lightning rods were based on sound principles. It should be noted that similar demonstrations had been performed in Europe, but Franklin's clear account made the connection widely known and encouraged the installation of the first protective rods.

The basic design of a lightning rod has changed remarkably little since Franklin's time. A metal rod, usually made of copper, is mounted vertically at the highest point of a building. A conductor cable runs from the rod down the outside wall and into the ground, where it is attached to a buried earth rod or plate. When lightning strikes, the current follows the path of least resistance along the cable and is carried safely into the soil, bypassing flammable roof timbers and interior spaces. The sharp tip of the rod is also believed to leak electrical charge gradually into the surrounding air, reducing the build-up that can trigger a strike. This simple arrangement remains the foundation of modern lightning protection.

Adoption of the new invention was not immediate everywhere, but it spread steadily. Franklin himself installed a rod on his own house in Philadelphia, and within a few years churches, public buildings and ships in North America and Europe were being fitted with them. In some communities there was religious opposition to the idea of interfering with what was seen as God's judgment, and a few critics argued that protecting buildings might provoke further divine punishment. Nevertheless, the practical benefits were so obvious that by the end of the eighteenth century lightning rods had become common on tall structures throughout Europe and the American colonies.

During the 1770s a curious scientific dispute arose over whether the tip of a lightning rod should be sharp or blunt. Franklin favoured the sharp point, arguing that it discharged a cloud gradually and could often prevent a strike altogether. Some British experimenters, however, preferred a blunt tip, claiming that sharp points actually attracted lightning rather than quietly releasing it. The debate eventually took on a political colour during the American Revolution, when Franklin's allegiance to the revolutionary cause led some institutions in Britain to favour blunt rods simply because pointed ones were associated with him. The argument continued for years, but later research showed that both forms can be effective when correctly installed.

Today, lightning protection systems are required by building codes in many countries for structures such as hospitals, factories, fuel stores and very tall buildings. Standards specify the types of metal to be used, the thickness of conductors, and the resistance of the connection to the ground. In addition, aircraft and wind turbines use similar principles to carry lightning currents away from sensitive equipment. Although the basic idea is more than 250 years old, lightning rods and their modern equivalents still prevent thousands of fires and deaths every year.

No lightning protection system, however, can guarantee complete safety. A rod protects only the building to which it is fitted, and poorly installed or damaged conductors may fail. Lightning can also cause side flashes to nearby objects or damage electrical devices through surges. Modern surge protectors can also shield electronic equipment from the indirect effects of a strike. Regular inspection and maintenance are therefore essential, particularly in regions with frequent storms. Despite these limitations, Franklin's invention remains one of the simplest and most effective safety devices ever devised. Its success lies in converting a sudden, unpredictable danger into a manageable flow of current along a known path.

The aurora is one of the most spectacular natural displays in the night sky. Bands, arcs and curtains of green, red and violet light appear in the polar regions, where they are known as the northern lights or aurora borealis in the north and the southern lights or aurora australis in the south. They occur most frequently in an oval band around each magnetic pole, known as the auroral oval. The lights can be still or can ripple and dance across the sky within seconds. For centuries they have inspired awe and curiosity, but their true origin lies far beyond the Earth, in the stream of particles that constantly flows from the Sun. The lights are best viewed on clear, dark nights away from city lights.

That stream is called the solar wind. It consists mainly of electrons and protons that are ejected from the Sun's outer atmosphere at speeds of hundreds of kilometres per second. When this wind reaches the Earth, it interacts with the planet's magnetic field, a region known as the magnetosphere. Most solar-wind particles are deflected around the Earth, but some become trapped and are guided along the invisible magnetic field lines towards the polar regions. This is why auroras are seen most often near the magnetic poles rather than at the equator. The speed and density of the solar wind vary with the solar cycle, which lasts about eleven years.

When the charged particles reach the Earth's upper atmosphere, they collide with atoms and molecules of gas. The collisions transfer energy to the gas particles, which then release that energy as light. The colour of an aurora depends on which gas is involved and the altitude at which the collision occurs. Oxygen atoms, for example, produce a green or red glow, while nitrogen molecules give rise to blue or purple hues. Because green light from oxygen is the most common emission, most auroras appear green to the human eye, but during strong displays other colours can become visible. The exact shade can shift quickly as conditions change.

Auroras occur at altitudes ranging from roughly eighty kilometres to several hundred kilometres above the ground. The lower edge of a typical green aurora is often around one hundred kilometres high, whereas red auroras, which are produced by oxygen at higher altitudes, can extend to three hundred kilometres or more. Altitude matters because the atmosphere becomes thinner and richer in different gases at different heights. An observer on the ground sees the combined effect of these layers, which explains why the bottom of an auroral curtain is frequently green while its top may be red. Auroras can also appear as faint greenish clouds rather than sharply defined curtains.

When the Sun is especially active, it can release enormous bursts of solar wind in events known as coronal mass ejections. These disturbances cause geomagnetic storms, during which the auroral oval expands towards lower latitudes. In rare historical storms, auroras have been observed as far south as the Caribbean and southern Europe, something that is normally impossible. Such storms can also disrupt radio communications, satellite electronics and electricity grids, so scientists monitor the Sun continuously in an effort to give warnings of particularly severe space weather. The most powerful geomagnetic storm on record occurred in 1859, when telegraph systems in Europe and North America were disrupted.

Before the scientific explanation was known, many cultures interpreted the aurora in supernatural terms. Scandinavian traditions sometimes described the lights as reflections from the shields of warrior maidens, while some Inuit groups saw them as spirits of the dead playing a game. In Norse mythology, the lights were sometimes linked to the mythical Bifröst bridge, although interpretations varied widely. The term aurora borealis was introduced in the early seventeenth century by the astronomer Galileo, who combined the name of the Roman goddess of dawn with the Greek word for the north wind. Systematic scientific study of the phenomenon, however, did not begin until the nineteenth century.

The foundations of this research were laid by the Norwegian scientist Kristian Birkeland, who in the early twentieth century proposed that charged particles from the Sun were guided towards the polar regions. Modern research relies on a combination of ground-based instruments and spacecraft. Networks of cameras and magnetometers around the polar regions record the position and intensity of auroras from one night to the next. Satellites such as NASA's THEMIS mission have measured the magnetic disturbances in the tail of the magnetosphere that trigger auroral activity. Scientists also use indices of geomagnetic activity, such as the Kp index, to forecast where and when auroras are likely to be visible. These forecasts are now accurate enough to guide photographers and tourists who travel to high-latitude locations in search of the lights.

Earth is not the only planet with auroras. Spacecraft have photographed auroras on Jupiter and Saturn, where the magnetic fields are far stronger than Earth's, and even on the outermost planets. The same physics applies whether the atmosphere is composed of oxygen, nitrogen or hydrogen. The presence of auroras on other worlds confirms that the basic mechanism is universal: charged particles from a star, guided by a magnetic field, strike a planetary atmosphere and make it glow. In this sense, the northern lights are a visible reminder of processes that operate throughout the solar system.

Few architectural movements have attracted as much public hostility as Brutalism. The word itself is often used as a term of abuse to describe buildings that appear massive, grey and unfeeling. Yet in recent years a growing number of architects, historians and residents have begun to argue that this reputation is unfair. In my view, the time has come for a more balanced assessment.

Brutalism was one of the most ambitious attempts in the twentieth century to use architecture as a tool for social improvement, and its best buildings deserve to be judged on their own terms rather than dismissed out of hand. Too many important structures have already been lost to demolition, and the debate is now urgent.

The term Brutalism derives from the French phrase béton brut, meaning raw concrete. It was associated in the 1950s with Le Corbusier, whose post-war buildings used untreated concrete as a deliberate aesthetic choice. Le Corbusier's Unité d'Habitation in Marseille, completed in 1952, demonstrated the expressive use of rough-cast concrete. In Britain the architects Alison and Peter Smithson designed a school at Hunstanton that displayed its steel frame and services openly, and the critic Reyner Banham later used the phrase 'the New Brutalism' to describe an approach that valued honesty of materials, structure and function. The movement came to stand for an architecture that refused to hide how it was made.

Brutalist buildings are typically composed of heavy, monolithic forms, often with exposed concrete surfaces marked by the texture of wooden formwork. They tend to be geometric and repetitive, with visible structural elements and little decorative ornament. Many were designed as public housing, universities, government offices and cultural institutions. Well-known examples include the National Theatre in London and the University of Toronto's Robarts Library. Their scale was intended to express permanence, order and civic pride, but it also made them appear severe to many eyes, and the bare concrete could seem cold and unwelcoming.

The movement reached its greatest influence in the 1960s and 1970s, when brutalist buildings were erected in cities across Europe, North and South America, and Asia. By the 1980s, however, the tide had turned. Many structures had weathered badly: concrete became stained with pollution, leaks appeared where joints had failed, and exposed surfaces looked shabby. At the same time, high-density estates came to be associated with poverty and crime, and local authorities began to demolish some of the most prominent examples. To the general public, Brutalism increasingly symbolised failed urban policy rather than the progressive ideals that had inspired it.

Critics of Brutalism raise serious points that should not be ignored. They note that many buildings were poorly constructed and expensive to maintain, with flat roofs that leaked and heating systems that failed. They also argue that the scale of some schemes overwhelmed the street, removed active frontages and made spaces around buildings feel unsafe. In some cases, the use of raw concrete in damp northern climates proved unsuitable, turning streaky and dark. Furthermore, the social ideals behind many projects were never matched by adequate investment, which meant that buildings failed their residents in practical ways quite separate from questions of style.

Despite these failures, a significant reappraisal has taken place. Buildings such as the Barbican Estate in London and the Park Hill estate in Sheffield have been listed or protected, and campaigns have successfully defended others, including Preston Bus Station. Some former council blocks have been renovated and have become desirable homes for new generations. Meanwhile, photographers and writers have celebrated what they see as the sculptural drama of these structures, and many examples have become popular subjects on social media. This shift suggests that public opinion is more complicated than simple hatred.

What explains this change? One factor is historical distance: buildings that once seemed threatening now read as monuments to a vanished confidence in public provision. Another is the recognition that many brutalist buildings are extraordinarily skilful pieces of design, with careful handling of light, mass and circulation. The raw concrete that was once seen as ugly is now appreciated for its texture and honesty. In addition, preservationists argue that demolition is wasteful and that adapting existing buildings is often more sustainable than replacing them, since the carbon already embodied in their construction would be lost.

I do not wish to suggest that every brutalist building is a masterpiece. Many are genuinely flawed, and some should never have been built. Nor do I believe that aesthetic judgments can be reduced to a political test. However, the blanket dismissal of Brutalism has prevented us from seeing the movement's real achievements. Where buildings can be repaired and adapted without compromising their architectural character, they should be given that chance. Demolition should be regarded as a last resort, not a first reaction to changing fashion.

A more informed debate about Brutalism would begin by separating the quality of individual buildings from the image of the movement as a whole. It would also acknowledge that failures were often failures of management and investment rather than of architectural ideas. Above all, it would recognise that buildings which once embodied hope can still be made to work. If we preserve only the styles we find immediately comfortable, we risk losing some of the most honest and original architecture of the twentieth century, and with them the lessons they teach about ambition, failure and renewal.