Celsius

Celsius (symbol °C) is a universal temperature scale. It is used to measure the temperature of air, the human body, water, and other substances. It is the most widely used temperature scale in the world on a daily basis, particularly in weather reports and health contexts.

The scale is based on two well-known states of water: freezing and boiling, at standard atmospheric pressure. The freezing point of water is set at 0 °C and the boiling point at 100 °C. The interval between them is divided into 100 equal parts, each representing one degree.

History

The scale takes its name from Anders Celsius, an eighteenth-century Swedish astronomer who proposed a temperature scale based on the states of water. The original version he presented had reversed numbers compared to what is used today. Later it was reversed so that 0 would be the freezing point and 100 the boiling point. The term "centigrade" was used for a long time, but "Celsius" was eventually adopted as the official name.

Relation to Kelvin

In the International System of Units (SI), the base unit of temperature is the kelvin (K). One degree Celsius and one kelvin are equal in size, but their starting points differ: absolute zero is the lowest possible temperature, equivalent to approximately −273.15 °C. Accordingly, to convert Celsius to kelvin, 273.15 is added.

Conversion to Fahrenheit

The Fahrenheit scale (°F) is still widely used in the United States. Conversion follows a simple formula: °F = (°C × 9/5) + 32. For example, 0 °C is 32 °F, and 100 °C is 212 °F. The two scales meet at −40, where the values are identical.

Use

Celsius is used in weather forecasting, food and cooking, industry, and scientific research. In health, normal human body temperature is measured at approximately 37 °C. Many countries worldwide use this scale as an official standard, though most scientific values are recorded in kelvin.