{"id":51662,"date":"2025-08-08T01:57:14","date_gmt":"2025-08-08T01:57:14","guid":{"rendered":"https:\/\/www.newsbeep.com\/uk\/51662\/"},"modified":"2025-08-08T01:57:14","modified_gmt":"2025-08-08T01:57:14","slug":"the-eiffel-tower-gets-bigger-every-summer-heres-why","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/uk\/51662\/","title":{"rendered":"The Eiffel Tower gets bigger every summer \u2013 here\u2019s why"},"content":{"rendered":"

The structure known today as the Eiffel Tower was originally dubbed the Tour de 300 m\u00e8tres, the 300-metre tower. The name was proposed by engineers Maurice Koechlin<\/a> and \u00c9mile Nougier<\/a> to Gustave Eiffel, who oversaw the tower\u2019s construction. It hinted at the desire to build something extraordinary, a technological feat that would set a new height record. <\/p>\n

However, as temperatures rise during the summer months, the Eiffel Tower grows even taller than its original design.<\/p>\n

A lightweight iron structure<\/p>\n

The Eiffel Tower was erected at the 1889 World\u2019s Fair<\/a> to commemorate the centenary of the French Revolution.<\/p>\n

Eiffel chose puddled iron<\/a> for its construction, a material he knew well and had used in previous projects with good results. This ferrous material<\/a> can withstand high levels of stress<\/a>, which allowed for the construction of a large, very light tower that would be safe from horizontal wind forces. <\/p>\n

To give an idea of how light the tower is, its weight of 7,300 tonnes is close to the weight of the volume of air contained within it \u2013 around 6,300 tonnes.<\/p>\n

The Eiffel Tower was intended to be a prime observation point, as well as a base for radio broadcasting. The tower itself is a gigantic triangular lattice structure<\/a>, much like the Garabit Viaduct (also designed by Eiffel\u2019s office) and the Forth Bridge in Scotland, both from the same period. <\/p>\n

All of these structures grow when the temperature of the material increases. However, unlike bridges, which behave in a more complex manner, the Eiffel Tower experiences mainly vertical growth and shrinkage due to changes in temperature. This phenomenon is known as thermal expansion<\/a>.<\/p>\n

Read more:
\n How the Eiffel Tower became silent cinema’s icon<\/a><\/p>\n

Materials that grow and shrink<\/p>\n

We know that most solids expand when the temperature rises and contract when it falls. This is because an increase in temperature causes greater agitation in the atoms, which leads to an increase in the average distance between them. <\/p>\n

Depending on the nature of the bond, different kinds of solids experience greater or lesser growth, which engineers have to record with great care. Ceramics and glasses, with stronger bonds, expand less than metals, which in turn expand less than polymers.<\/p>\n

So, how can we estimate the amount of movement in a solid? When the elements are straight \u2013 as is the case in most public works and architecture, where beams and bars predominate \u2013 the movement is proportional to three parameters: the length of the element, the change in its temperature, and the material\u2019s coefficient of expansion<\/a>.<\/p>\n

A hair\u2019s breadth<\/p>\n

Many ceramic materials typically have expansion coefficients ranging from 0.5×10\u207b\u2076 to 1.5×10\u207b\u2076 (\u00b0C) \u207b\u00b9, while metals range between 5×10\u207b\u2076 and 30×10\u207b\u2076 (\u00b0C)\u207b\u00b9, and polymers between 50×10\u207b\u2076 and 300×10\u207b\u2076 (\u00b0C)\u207b\u00b9. These (perhaps strange-looking) numbers indicate the growth of a standard-length unit when the temperature rises by one degree Celsius. <\/p>\n

The most expandable materials are polymers, which expand about ten times more than metals, and metals expand ten times more than ceramics. <\/p>\n

The puddled iron used in the Eiffel Tower, and its steel components, have a coefficient of around 12×10\u207b\u2076 (\u00b0C)\u207b\u00b9, meaning that a one-metre-long iron bar expands by 12×10\u207b\u2076 metres when the temperature rises by one degree. That is just a dozen microns<\/a>, less than the thickness of a human hair. <\/p>\n

So does heat have any noticeable effect on buildings? Yes, if we take into account that there are two other parameters to consider: the length of the element and the temperature range where it is located.<\/p>\n

\"\"<\/a><\/p>\n

The Garabit Viaduct. When it was completed in 1884, it was the longest arch bridge in the world.
\n Wikimedia commons<\/a>, CC BY<\/a><\/p>\n

The length can be very great. The Eiffel Tower is 300 m high, but the Garabit Viaduct<\/a> is 565m long, and the Forth Bridge is over 2.5km long. Today there are many larger linear structures, and thermal expansion also affects the railway tracks that many bridges are built to carry.<\/p>\n

Read more:
\n Baltimore bridge collapse: a bridge engineer explains what happened, and what needs to change<\/a><\/p>\n

Historical temperature ranges must also be analysed. Paris has been recording temperatures for more than two centuries, with winter minimums below -20\u2070C and summer maximums of around 40\u2070C. We should also take into account the effect of solar radiation \u2013 metals can reach much higher temperatures in direct sunlight, often exceeding 60\u2070C or 70\u2070C. <\/p>\n

\"\"<\/a><\/p>\n

The Forth Bridge, an arch railway bridge that crosses the Firth of Forth in eastern Scotland.
\n Wikimedia commos<\/a>, CC BY<\/a><\/p>\n

Leaning away from the sun<\/p>\n

Now, let\u2019s do the maths. We\u2019ll estimate how much a simple 100-metre-long metal bar expands when the temperature fluctuates by 100\u2070C \u2013 the approximate range experienced by the Eiffel Tower.<\/p>\n

The calculation is simple. If a one-metre bar expands by 0.000012 metres when the temperature rises by one degree, a 100-metre bar expands by 0.12 metres when the temperature rises by 100 degrees. And a 300-metre bar would expand three times as much: 0.36 metres. That is, 36 cm. This is a noticeable difference.<\/p>\n

Clearly, a simple bar does not behave the same as a tower made of more than 18,000 pieces of riveted iron oriented in all directions. Furthermore, the sun always shines on one of its sides. This means one of its faces grows more than the others, causing a slight curve in the tower, as if it were leaning away from the sun. <\/p>\n

Specialists have estimated that the Eiffel Tower actually grows between 12 and 15 centimetres when comparing its size on cold winter days with the hottest days of summer. This means that, in addition to being a landmark, a communications tower and a symbol of Paris itself, the Eiffel Tower is also, in effect, a giant thermometer.<\/p>\n","protected":false},"excerpt":{"rendered":"The structure known today as the Eiffel Tower was originally dubbed the Tour de 300 m\u00e8tres, the 300-metre…\n","protected":false},"author":2,"featured_media":51663,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[31],"tags":[6225,6485,6486,1120,96,56,54,55],"class_list":["post-51662","post","type-post","status-publish","format-standard","has-post-thumbnail","category-arts-and-design","tag-arts","tag-arts-and-design","tag-artsanddesign","tag-design","tag-entertainment","tag-uk","tag-united-kingdom","tag-unitedkingdom"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/51662","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/comments?post=51662"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/51662\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media\/51663"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media?parent=51662"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/categories?post=51662"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/tags?post=51662"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}