Fahrenheit
Abbreviation/Symbol:
℉
Wordwide use:
The Fahrenheit scale was replaced by the Celsius scale in most countries during the mid to late 20th century, although Fahrenheit remains the official scale of the United States, Cayman Islands and Belize.
Canada retains Fahrenheit as a supplementary scale that can be used alongside Celsius, and in the UK the Fahrenheit scale continues to be used informally, especially in terms of expressing hot weather (although colder weather is generally expressed using Celsius).
Definition:
Fahrenheit is a thermodynamic temperature scale, where the freezing point of water is 32 degrees Fahrenheit (℉) and the boiling point 212℉ (at standard atmospheric pressure). This puts the boiling and freezing points of water exactly 180 degrees apart. Therefore, a degree on the Fahrenheit scale is 1/180 of the interval between the freezing point and the boiling point of water. Absolute zero is defined as -459.67℉.
A temperature difference of 1℉ is the equivalent of a temperature difference 0.556℃.
Origin:
Proposed in 1724 by, and named after, the German physicist Daniel Gabriel Fahrenheit (1686–1736). Fahrenheit pioneered the manufacture of thermometers using mercury, and established 0℉ as the stabilized temperature when equal amounts of ice, water, and salt are mixed. He then defined 96℉ as the temperature "when the thermometer is held in the mouth or under the armpit of a living man in good health".
Subsequently, the freezing temperature of water has been redefined as exactly 32℉, and normal human body temperature as 98.6℉.
Common references:
Absolute Zero, -459.67℉
Freezing point of water, 32℉
Warm summer's day in a temperate climate, 72℉
Normal human body temperature, 98.6℉
Boiling point of water at 1 atmosphere, 212℉
Usage context:
The Fahrenheit scale was replaced by the Celsius scale in most countries during the mid to late 20th century, although Fahrenheit remains the official scale of the United States, Cayman Islands and Belize.
Canada retains Fahrenheit as a supplementary scale that can be used alongside Celsius, and in the UK the Fahrenheit scale continues to be used informally, especially in terms of expressing hot weather (although colder weather is generally expressed using Celsius).
Why can you not go below -459.67°F?:
The temperature -459.67°F is known as absolute zero and it is the lowest possible temperature that can exist in the universe. At this point all molecular motion ceases and no further fall in temperature is possible since the kinetic energy of particles is at zero and they come to a complete standstill.
The Kelvin and Rankine scales start at absolute zero.
Going below -459.67°F or 0R is impossible because it contradicts the laws of thermodynamics. The energy of particles in an object decreases as they lose kinetic energy and their ability to move. At absolute zero the particles have no energy to give up making any further fall in temperature impossible as this would require them to have negative energy which is not possible.
Is there an absolute Fahrenheit scale?:
The freezing point of water is defined as 32 degrees Fahrenheit (°F) and the boiling point of water is defined as 212 °F. These reference points were first based on the freezing and boiling points of a mixture of salt ice.
Rankine has the same intervals as the Fahrenheit scale but it is an absolute temperature scale and so it starts at absolute zero which is the lowest possible temperature that can be achieved. This makes Rankine and absolute variant of Fahrenheit.
This means that it is simple to convert Rankine to Fahrenheit; you simply add 459.67. Similarly, to convert Fahrenheit to Rankine, subtract 459.67.
For example, a temperature of 500 Rankine is 40.33 Fahrenheit.
