Otto von Guericke was the first who experimentally demonstrated cloud formation by expanding and cooling of compressed air before 1663. Scientists initially grappled with the very question of why clouds float. Early explanations were hampered by limited theory, imprecise instruments, and gaps in meteorological knowledge.First attempts for distinguishing various cloud types arose towards the end of the 18th century. A key turning point came in 1803 when Howard proposed a first systematic scheme using Latin terminology for different cloud types. This effort laid the cornerstone for what would evolve into today's internationally recognized cloud classification system. The path to accurate understanding was long and iterative; early laboratory work and imprecise instruments produced repeated misjudgements that endured for decades. Manned balloon ascents provided direct measurements of meteorological parameters in the free atmosphere and in clouds, but more reliable and bias-free instruments and advances in theory were necessary to achieve reliable results.Additional techniques had to be developed to determine cloud altitudes and track their motion, gaining knowledge of vertical temperature and moisture profiles that shape different cloud types. Beginning in the 1890s, large-scale movements in the upper atmosphere were recognised by coordinated international observations.Contemporary early cloud atlases were published despite the limitations of low-contrast, poor photographs. Alternatives, like paintings or cloud watercolours, were even used to overcome these early hurdles. Coordinated observations using daily pilot balloons, kites, and later weather aircraft allowed researchers to further explain cloud formation both in stable and unstable atmospheric conditions. In addition, stratospheric and mesospheric clouds were discovered.After many efforts to publish international and national cloud atlases the World Meteorological Organization's founding in 1951 enabled the first modern International Cloud Atlas in 1956, standardising cloud observation practices and nomenclature.
This article examines the foundational role of Cevat Eyüp Taşman (1893–1956), Türkiye's first petroleum geologist, by analyzing how his higher education in the United States and his professional experience with international oil companies established him as essential “critical human capital” for the Republic. Drawing on archival documents and primary sources, the study focuses on the period from his initial involvement in 1929 until his death in 1956. It structures his contributions around four foundational pillars that transformed the national oil enterprise: the technical-scientific pillar, established through systematic field research and global publications; the institutional pillar, realized by founding and leading national exploration bodies; the legal-regulatory pillar, marked by his pivotal role in drafting Petroleum Law No. 6326 (1954); and the intellectual-public pillar, demonstrated by his leadership in professional societies and public pedagogy. The research repositions Taşman not only as a technical expert but also as a “public intellectual” who consistently aligned scientific knowledge with national development objectives. Accordingly, his legacy is assessed through these four pillars, which together underscore his enduring influence on Türkiye's quest for energy independence.
In October 1929, measurements of the atmospheric potential gradient (PG) began to be routinely recorded at the Magnetic Observatory in Świder, Poland. This started a new chapter in the history of the Observatory, in 1937 renamed the Geophysical Observatory in Świder. Two Benndorf electrometers recorded continuously until September 1939. War World II disrupted these observations as well as shattered efforts to publish the results of nearly a decade. Nevertheless, these early actions initiated by the Observatory management shaped its future as it became a contemporary atmospheric electricity station in the second half of the 20th century.
Three historic tide gauge records from the Arctic archipelago of Svalbard have been converted from tabulations more than one century old into computer files. The records are found to be good quality and capable of being used in modern tidal analysis. The analyses confirm the findings on tidal constants by previous researchers and demonstrate how little non-tidal variability in sea level there was at these times. One of the tide gauges used was a crude contraption of a design not used before or since. Nevertheless, it appears to have worked well and so deserves to be better known.
A lower Paleozoic slab of oceanic lithosphere was obducted onto the southern margin of Avalonia during the Variscan orogeny and is now exposed throughout the Lizard District of Cornwall, England. This complexly faulted and metamorphosed region of mafic and ultramafic rocks has been the subject of geological investigation for over two hundred years. Herein the most significant scientific contributions made over a sixty-five-year interval from 1818 to 1883 are reviewed. Early workers, including Ashurst Majendie, Adam Sedgwick, John Rodgers, and Henry De la Beche, conducted field-based studies of the region, making lithologic observations and mapping contacts between the major rock units. Subsequently, an intense phase of investigation into the processes and products of contact and regional metamorphism in Cornwall and the Lake District informed and inspired the field and microscopical studies of the Lizard District by Thomas G. Bonney. Detailed consideration of the pioneering work of these 19th century geologists provides insights into their methodologies as well as an evolving understanding of the complex and enigmatic rocks of the Lizard.
Point discharge, like lightning, is an atmospheric electricity process which has been observed directly and indirectly for centuries. Point discharge occurs when an electric field is enhanced at a point, causing local ionisation of the air and allowing a current to flow between the object and atmosphere. Point discharge sensors are simple instruments which measure the discharge currents caused by enhancements of the atmospheric electric field. In the early 20th Century, several milestone atmospheric electricity investigations were performed which employed the effects of naturally occurring point discharge currents and the measurements made by point discharge sensors. Point discharge was central to some of the arguments made in the proposal of the global atmospheric electric circuit, and the early evidence that was found to support this model. Point discharge sensors continued to be used throughout the 20th and 21st centuries, with understanding of their operations being developed further in this time.
Over the past decade, geological and historical evidence has increasingly suggested the existence of a vast ancient lake in central Iran, herein referred to as the Paleo Mega Lake of Rey (PAMELA). This study employs an interdisciplinary methodology to identify and geographically correlate historical references and terminologies associated with the lake. By analyzing over 350 sources, including travelogues, city histories, and ancient religious texts, we reconstructed the probable location, hydrological timeline, and cultural impact of the lake. Findings suggest that PAMELA has been referenced by various historical names such as Faraxkurt and Saveh Lake, and that it significantly influenced the livelihood of ancient communities. The integrated analysis points to a high probability of sustained water presence between 10 000 BCE and the 6th century CE.
Paul J. Crutzen was a brilliant scientist and a pioneer in atmospheric sciences. At the same time, he was a kind-hearted, humorous and pleasant person. Paul was deeply empathetic toward the personal lives of his colleagues and students, always making time for those around him – especially his family. This tribute brings together a series of anecdotes shared by friends and colleagues, offering a more intimate portrait of the man behind the science. Collectively, these reflections reveal aspects of Paul Crutzen that may be overlooked when focusing solely on his extraordinary scientific accomplishments; however, they were integral to his ability to achieve them.
The Veramin meteorite, believed to have fallen in 1880, near Varamin, Tehran province, Iran (then Persia), is one of few witnessed falls of a mesosiderite, a rare type of stony-iron meteorite. In this review, it is described that historical records show inconsistencies regarding the fall, and consequently, the naming of the meteorite. The earliest printed account, by Ferdinand Dietzsch in 1881, reported that the meteorite fell near the village “Karand” east of Tehran, with a thunder-like sound. The Shah had ordered an examination of it. Later, meteoricist Aristides Brezina named it “Veramin”. Further historical accounts include descriptions by Iranian official Mohammad Hassan Khan Sani' od-Dowlah and the explorer Sven Hedin. A key document is a Persian text on a cardboard, preserved with the main meteorite mass in Tehran's Golestan Palace. Members of the nomadic Shahsevan-e Baghdadi tribal confederacy, who had winter settlements west of Tehran, are reported as eyewitnesses. The geologist Henry A. Ward provided a detailed description in 1901, confirming the meteorite's composition and securing a larger mass for analysis and distribution to museums. The exact location and date of the fall remain uncertain due to imprecise and conflicting sources. The most likely impact field is the Booghin-Eshtehard area west of Tehran, with the event happening sometime in the period February to April 1880. The original mentioning of “Karand” is a confusion with Zarand(ieh), 70 km to the west of Varamin.
Aurora records are a valuable proxy for understanding historical solar behavior. This study explores historical records of auroras reported in the Spanish newspaper Extremadura
The founder of soil mechanics, Karl Terzaghi, took the initiative in 1954 to contact the Danish engineer Laurits Bjerrum, requesting to meet. Terzaghi wanted to meet the engineer who had written a paper on the stability of the unusual Norwegian quick clays at the European Slope Congress in Stockholm. Bjerrum was 36 years old at the time, had a PhD and was already director of the NGI (Norges Geotekniske Institutt – Norwegian Geotechnical Institute). From his position as director of the NGI, he was actively involved in many varied consultancies, placing great value on the continuous interaction between practice and research. Bjerrum's strategy for establishing the NGI came from the experience of other research centres such as the BRS (Building Research Station) in Great Britain and Imperial College London. In addition, having lived through the Nazi occupation of Denmark, he was predisposed to be against the misuse of authority and established an open structure for the institute from its inception. Bjerrum was in close contact with the Norwegian Institution of Technology, and, in 1952, he succeeded in getting soil mechanics incorporated as a compulsory subject in the civil engineering degree. Subsequently, in 1960, the Chair of Soil Mechanics and Foundation Engineering was established. The first laboratory of this chair was equipped with material donated by the NGI. Bjerrum died young (54 years old), but he had built an excellent reputation through his work at the NGI and his contributions to international conferences, where he maintained a close relationship with the significant figures in geotechnics: Terzaghi, Skempton, Peck and Casagrande. He made regular trips to the USA, where he was a visiting professor at MIT (Massachusetts Institute of Technology) and received the highest international decorations.
The agonic line, which represents geomagnetic declinations of 0°, recently crossed the Royal Observatory of Madrid (ROM) in December 2021, causing a shift in declination values from west to east. This event constitutes a notable milestone for this significant observatory, where the first geomagnetic observation series commenced around 1855 in Spain. In this work, taking advantage of the occurrence of this event, a detailed study has been conducted to investigate the historical evolution of the magnetic declination at the ROM to decipher prior occurrences of the agonic line crossing this place. Despite the ROM having hosted the first series of geomagnetic measurements in Spain, the present lack of geomagnetic measurements in this observatory makes it necessary to extend the declination measurements to other observatories distributed throughout the Iberian Peninsula to better define the passage of the agonic line since 1855 up to the present. For epochs prior to 1855, a bibliographic search for declination measurements conducted in the Iberian Peninsula has been carried out, complemented by historical data from the HISTMAG database. As a result, a time-continuous curve of geomagnetic declination is generated from 1590 to 2022 at the ROM coordinates. The declination curve reveals that the agonic line also crossed the ROM 400 years ago (around 1600), passing from western to eastern declination values.
After a brief introduction to encyclopedias, the explanation of lightning and thunder in well-known encyclopedias, from the works of Greek philosophers to encyclopedias of modern physics, is examined. Starting with Aristotle (who is not regarded as an encyclopedist but is very important for our topic), 10 out of more than 200 known encyclopedias are treated in some detail. This selection is certainly somewhat arbitrary, but it an attempt was made to choose encyclopedias which are highlights and which were widely circulated at their time. In antiquity and during the Middle Ages, the explanations of thunderstorms were generally quite different from the modern view, explaining, for instance, lightning as a consequence of thunder. Besides this, strange effects of lightning were often reported. Many authors of those times used the explanations of former encyclopedias, sometimes referring to earlier authors, often just plagiarizing. These ideas, unorthodox by our present understanding, persisted for almost 2 millennia in encyclopedias. From the middle of the 18th century onward, physical explanations began to emerge; these are still valid today. More and more correct details regarding lightning and thunder and the results of experiments have been reported in encyclopedias. It is also attempted in this paper to name the insights of other scientists which the authors of contemporary encyclopedias do not mention but which should have been available at the time. Finally, it is stated that, even today, several details regarding thunderstorms are not well understood.
The measurement series of the three geomagnetic observatories Potsdam, Seddin and Niemegk spans more than 130 years, starting in 1890. It is one of the longest, almost uninterrupted series of recordings of the Earth's magnetic field. Data users frequently emphasise the high quality of the data and their significance for geomagnetic base research. Very well known outstanding geomagnetism scientists, such as Max Eschenhagen, Adolf Schmidt, Julius Bartels, Gerhard Fanselau and Horst Wiese, directed the three observatories in historical sequence.This paper describes the history of the Niemegk Adolf Schmidt Observatory, which was started in 1932 and is currently still in operation.
From 1901 to 1912 – known as the “heroic period” of Arctic and Antarctic exploration – great inroads were made (not only geographic but also scientific) to our knowledge of the continent. At Amundsen's Expedition through the Northwest Passage, measurements of the geomagnetic field and visual auroras were carried out for 19 months at Gjoa Haven (Gjøahavn in Norwegian; geographic coordinates 68°37′10′′ N, 95°53′25′′ W). Scott's DiscoveryAuroras were observed during 7 months per year. This gave a unique possibility to compare conjugate characteristics of polar cap auroras. Comparing conjugate geophysical data introduces some difficulties. During the winter season at Gjoa Haven, they had a bright summer in Antarctica, and visa versa. Thus, simultaneous temporal and spatial ionospheric variations can be marked differently. Still, the average diurnal and seasonal variations were similar. The quantity of the auroral data from Cape Armitage was larger because there they had a continuous watch of the sky.The main findings regarding polar cap auroras are the following. Three different auroral forms dominate the polar cap. Low-intensity auroral bands – then called streamers – were the dominating auroral forms morning and afternoon. The number of auroral events in 1903 was nearly twice that in 1902 and 1904. A marked midwinter maximum was observed at both stations. Many displays were observed poleward of the oval. The large fraction was associated with weak magnetic disturbances.Some forms of polar cap aurora have special magnetic signatures and seem to be anti-correlated with Kp. They can be mapped even if they are not seen. According to recent satellite measurements (Newell et al., 2009), they are probably caused by polar rain and/or photoelectrons.