Celsius and Fahrenheit are the two most common temperature scales used around the world. While Celsius is the standard in most countries for everyday temperature measurements and scientific applications, Fahrenheit is primarily used in the United States. Understanding the differences between these scales, their origins, and how to convert between them is crucial in a globalized world. This article provides a comprehensive comparison of Celsius and Fahrenheit, exploring their definitions, history, usage, and relationship to other temperature scales.
What are Celsius and Fahrenheit?
The Celsius and Fahrenheit scales are named after the scientists who developed them, Anders Celsius and Daniel Gabriel Fahrenheit, respectively. Both scales are interval scales, meaning the difference between each degree is consistent, but they have different starting points and degree sizes.
Celsius Scale:
The Celsius scale, originally known as the centigrade scale, was devised by Swedish astronomer Anders Celsius in 1742. It is defined based on the properties of water. Originally, 0°C was set as the freezing point of water and 100°C as the boiling point of water at standard atmospheric pressure. While the modern definition is more precise, based on the triple point of water and absolute zero for scientific accuracy, for practical purposes, the freezing and boiling points of water remain key reference points. The unit increment is the degree Celsius (°C).
Fahrenheit Scale:
The Fahrenheit scale was established by German-Dutch physicist Daniel Gabriel Fahrenheit in 1724. Fahrenheit originally defined his scale using a mixture of ice, water, and salt for 0°F, and the temperature of the human body for around 96°F. He later refined it to use the freezing point of water at 32°F and the boiling point of water at 212°F. This set the difference between freezing and boiling points of water at 180 degrees Fahrenheit. The unit increment is the degree Fahrenheit (°F).
Key Differences Between Celsius and Fahrenheit
While both scales measure temperature, they differ significantly in their reference points, degree size, and global usage.
Freezing and Boiling Points of Water
The most prominent difference lies in the temperatures assigned to the freezing and boiling points of water:
- Celsius: Water freezes at 0°C and boils at 100°C. This 100-degree interval makes the Celsius scale convenient for many scientific and everyday applications.
- Fahrenheit: Water freezes at 32°F and boils at 212°F. The 180-degree interval between these points is a defining characteristic of the Fahrenheit scale.
Size of a Degree
Another crucial difference is the size of each degree unit:
- A degree Celsius is larger than a degree Fahrenheit. Specifically, one degree Celsius is equal to 1.8 degrees Fahrenheit (or 9/5 °F). Conversely, one degree Fahrenheit is equal to 5/9 of a degree Celsius.
Global Usage
The usage of Celsius and Fahrenheit varies geographically and by application:
- Celsius: It is the standard unit of temperature in the International System of Units (SI) and is used by most countries worldwide for weather forecasts, scientific research, and general temperature measurements.
- Fahrenheit: Primarily used in the United States, its territories, and a few other countries for everyday temperature reporting, especially in weather forecasts. However, even in these regions, scientific and technical fields predominantly use Celsius.
Converting Between Celsius and Fahrenheit
Being able to convert between Celsius and Fahrenheit is essential for understanding temperature information across different regions and contexts. Here are the formulas for conversion:
Celsius to Fahrenheit:
°F = (°C × 9/5) + 32
Fahrenheit to Celsius:
°C = (°F – 32) × 5/9
For example, to convert 25°C to Fahrenheit:
°F = (25 × 9/5) + 32 = 45 + 32 = 77°F
To convert 68°F to Celsius:
°C = (68 – 32) × 5/9 = 36 × 5/9 = 20°C
When to Use Celsius vs. Fahrenheit
The choice between Celsius and Fahrenheit often depends on the context and location:
- Scientific and International Communication: Celsius is almost universally preferred in scientific fields, international collaborations, and most parts of the world due to its standardization within the SI system.
- Everyday Use in the United States: Fahrenheit remains common for daily weather reports, cooking temperatures, and personal comfort levels in the U.S.
- Historical and Cultural Context: In some English-speaking countries outside the U.S., particularly older generations might still be familiar with Fahrenheit, especially for weather.
History of Celsius and Fahrenheit Scales
Anders Celsius (1701-1744): A Swedish astronomer, physicist, and professor, Anders Celsius introduced his temperature scale in 1742. Initially, his scale had 0 degrees as the boiling point of water and 100 degrees as the freezing point, but it was later reversed to the scale we use today, often attributed to Carl Linnaeus.
Daniel Gabriel Fahrenheit (1686-1736): A Polish-born, Dutch-German physicist and instrument maker, Fahrenheit developed his scale in the early 18th century. His mercury thermometer was a significant advancement, and his temperature scale gained prominence, particularly in English-speaking countries.
Celsius and Fahrenheit in Relation to the Kelvin Scale
Both Celsius and Fahrenheit are related to the Kelvin scale, which is the SI base unit of temperature and an absolute thermodynamic temperature scale. Absolute zero, the coldest possible temperature, is 0 Kelvin (0 K).
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Kelvin and Celsius: The Kelvin scale is directly offset from the Celsius scale. 0 K is equal to -273.15°C. The size of one Kelvin is the same as one degree Celsius. The conversion is: K = °C + 273.15.
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Kelvin and Fahrenheit: The relationship between Kelvin and Fahrenheit is less direct, involving both a scale shift and a degree size difference.
- K = (°F + 459.67) ÷ 1.8
- °F = (K × 9/5) − 459.67
Quick Comparison Table
For a quick overview, here’s a comparison table of key temperatures in both Celsius and Fahrenheit:
| Temperature Point | Celsius (°C) | Fahrenheit (°F) |
|---|---|---|
| Absolute Zero | -273.15 | -459.67 |
| Lowest recorded surface temperature on Earth | -89 | -128.2 |
| Melting point of ice | 0 | 32 |
| Average human body temperature | 37.0 | 98.6 |
| Boiling point of water | 100 | 212 |
| Highest recorded surface temperature on Earth | 58 | 136.4 |
| Surface of the Sun | 5526 | 9980 |
Side-by-side comparison of Celsius and Fahrenheit thermometers illustrating the different scales, with key reference points like the freezing point of water at 0°C and 32°F, and the boiling point at 100°C and 212°F.
Conclusion
Understanding the difference between Celsius and Fahrenheit is more than just knowing conversion formulas. It involves appreciating their historical context, recognizing their different reference points, and being aware of their global usage. While Celsius has become the international standard, Fahrenheit remains relevant in specific regions, particularly in the United States. Knowing both scales enhances communication and understanding in a world where temperature information is readily exchanged across different systems.
References
Diffen.com. Diffen LLC, n.d. Web. https://www.diffen.com/difference/celsius-vs-fahrenheit
