Celsius

Celsius
Name	Anders Celsius
Birth date	27 November 1701
Death date	25 April 1744
Nationality	Swedish
Known for	Celsius temperature scale, geodesy, astronomy
Fields	Astronomy, Geodesy
Workplaces	Uppsala University
Notable works	"Observations Célestes", meridian arc measurement

Celsius

Anders Celsius (27 November 1701 – 25 April 1744) gave his name to the Celsius temperature scale, an interval-based thermometric scale widely used in scientific, meteorological, industrial, and everyday contexts. His work in astronomy and geodesy at Uppsala University and participation in international expeditions connected him with contemporary figures and institutions across Europe, shaping empirical standards during the Enlightenment. The term "Celsius" denotes both the scale and the unit of temperature measurement employed in most countries and in virtually all scientific literature.

History

Celsius emerged from 18th-century efforts to standardize measurement among astronomers and geodesists collaborating across Royal Society, Académie des Sciences, and university observatories such as Uppsala University and Paris Observatory. Anders Celsius devised an early version of the scale in 1742 while corresponding with contemporaries including Georg Brandt and engaging with projects like the measurement of the meridian arc between Danish and Swedish territories. Subsequent refinements involved figures and institutions such as René Antoine Ferchault de Réaumur, Daniel Gabriel Fahrenheit, and the Royal Society of London, which compared thermometric standards across Europe. In the 19th century, adoption of a reversed orientation and later legal definitions were influenced by committees and standards bodies including International Committee for Weights and Measures and national metrology institutes like Physikalisch-Technische Bundesanstalt and National Institute of Standards and Technology. International metrology efforts tied Celsius to the kelvin as an SI-derived unit, with work by the International Bureau of Weights and Measures shaping the modern relationship between temperature scales.

Definition and scale

The Celsius scale is an interval scale defined relative to fixed thermodynamic points established through agreements among metrology organizations such as International Committee for Weights and Measures and the International Bureau of Weights and Measures. Historically anchored to the freezing and boiling points of water at standard atmospheric pressure—observations made at institutions like Royal Society-affiliated laboratories and University of Cambridge research facilities—the contemporary definition ties the degree Celsius to the kelvin via the relation °C = K − 273.15, a decision formalized by bodies including General Conference on Weights and Measures. The scale is linear: equal increments correspond to equal changes in thermodynamic temperature as defined by measurements at laboratories like National Physical Laboratory and Physikalisch-Technische Bundesanstalt using internationally recognized fixed points and primary thermometry methods.

Usage and notation

Notation conventions for Celsius follow standards set by organizations such as the International Organization for Standardization and the International Bureau of Weights and Measures. The unit symbol is "°C", recommended in technical publications from institutions like World Meteorological Organization, European Centre for Medium-Range Weather Forecasts, and NASA. In scientific texts produced at universities including Massachusetts Institute of Technology and University of Oxford, the Celsius degree is treated as a derived unit related to the kelvin; editors and publishers such as Nature Publishing Group and American Physical Society apply style rules that reference these bodies. Legal and regulatory usage in countries represented by agencies like National Institute for Public Health and the Environment and Health Canada prescribes Celsius for reporting ambient temperatures and public health thresholds. Historical notations and thermometer manufacturing practices were influenced by makers and institutions like Royal Society instrument collections and workshops in cities such as Stockholm and Amsterdam.

Conversion to other temperature scales

Conversion relations between Celsius and other temperature scales are standard among metrology and scientific organizations. Celsius and kelvin are linked by °C = K − 273.15, a convention used by International Bureau of Weights and Measures and taught at institutions such as Harvard University and Sorbonne University. Conversions with the Fahrenheit scale—used historically and currently in jurisdictions like United States and in documents from bodies such as National Weather Service—use the formula °F = (°C × 9/5) + 32, a relation originating in thermometry work by Daniel Gabriel Fahrenheit and later codified by international standards committees. Relations with the Rankine and Réaumur scales are likewise defined in metrology texts from institutions like Physikalisch-Technische Bundesanstalt and International Organization for Standardization for interoperability in engineering and archival research contexts.

Scientific and practical applications

Celsius is ubiquitous in scientific research across disciplines housed at organizations such as European Organization for Nuclear Research, Max Planck Society, and Smithsonian Institution, where experiments, climate studies, and laboratory protocols use degrees Celsius for reporting and control. Meteorological services including Met Office, Météo-France, and Japan Meteorological Agency issue forecasts and climate datasets in Celsius. Industrial standards bodies like International Electrotechnical Commission and European Committee for Standardization specify Celsius in manufacturing, quality control, food safety regulations enforced by Food and Agriculture Organization-referenced frameworks, and clinical environments overseen by agencies such as World Health Organization. Applications range from cryogenics research at facilities like CERN to everyday cooking and household thermostats regulated by municipal authorities in capital cities like London, Tokyo, and Stockholm.

Cultural and regional adoption

Celsius adoption varies by country and region, influenced by historical ties to scientific institutions and national standards agencies such as National Institute of Standards and Technology, Physikalisch-Technische Bundesanstalt, and Bureau International des Poids et Mesures. Most countries affiliated with World Meteorological Organization and the European Union report temperatures in Celsius; notable exceptions include the United States, where Fahrenheit remains common in public weather services and cultural practice. Regional education systems at universities such as University of Melbourne and University of Toronto teach thermometry including Celsius conventions, shaping public familiarity in Australia, Canada, and Europe. International events and agreements—convened by entities like United Nations and scientific congresses hosted by organizations such as International Union of Pure and Applied Physics—have reinforced Celsius as the prevailing unit for global scientific communication.

Category:Temperature scales