Degree (temperature)

A degree, when referring to temperature, is a unit of measurement representing a specific interval on a defined temperature scale. It is used to quantify the level of hotness or coldness of a substance or environment. Different temperature scales utilize different degree intervals and zero points, leading to varying numerical values for the same temperature.

The most common temperature scales employing degrees are:

• Celsius (°C): A metric scale where 0°C is defined as the freezing point of water and 100°C is defined as the boiling point of water at standard atmospheric pressure. Historically based on Anders Celsius' original 1742 scale with reversed values, it's now defined by the Kelvin scale, where 0°C is equivalent to 273.15 K. Celsius is widely used in most of the world for everyday temperature reporting.

• Fahrenheit (°F): A scale primarily used in the United States and a few other countries. On this scale, 32°F is defined as the freezing point of water and 212°F is defined as the boiling point of water at standard atmospheric pressure.

• Rankine (°R or °Ra): An absolute thermodynamic temperature scale, meaning its zero point is absolute zero (the theoretical point where all molecular motion ceases). Each degree Rankine is equal in size to one degree Fahrenheit. The freezing point of water is 491.67 °R.

The conversion between Celsius and Fahrenheit is:

• °F = (°C × 9/5) + 32
• °C = (°F - 32) × 5/9

The Kelvin scale does not use degrees; it uses Kelvins (K). Conversion between Celsius and Kelvin is:

• K = °C + 273.15
• °C = K - 273.15

It is important to specify the temperature scale (e.g., °C, °F) when reporting a temperature in degrees to avoid ambiguity. The context often implies the scale, but explicit notation ensures clear communication.