Fahrenheit

The Fahrenheit scale is a way to measure temperature. It was made by a scientist named Daniel Gabriel Fahrenheit in 1724. He picked special points for the scale, like when water freezes and the temperature of a human body. These points were later changed to make them easier to use. Today, pure water freezes at 32 °F and boils at 212 °F under normal air pressure.

For many years, the Fahrenheit scale was very important, especially in the United States. It is still used there and in a few other places like Palau, the Federated States of Micronesia, and the Marshall Islands. Some other countries, like Antigua and Barbuda and the Bahamas, also use it sometimes with another scale called Celsius.

Most countries now use the Celsius scale because it is easier for many uses. But learning about Fahrenheit is helpful because you will see it used in weather reports, cooking, and other places in some parts of the world.

Definition and conversion

On the Fahrenheit scale, water freezes at 32 °F and boils at 212 °F. This means there are 180 steps between freezing and boiling on this scale. Each step on the Fahrenheit scale is a little smaller than on the Celsius scale, where water freezes and boils are only 100 steps apart.

The two scales cross at -40; -40 °F is the same as -40 °C. Absolute zero, the coldest possible temperature, is 0 K, which is -273.15 °C or -459.67 °F. The Fahrenheit scale uses the same size steps as the Rankine scale but starts at absolute zero, just like Kelvin starts at absolute zero for the Celsius scale.

History

Fahrenheit created his temperature scale in 1724. He picked two important temperature points for his scale. The first point, 0 °F, was a very cold mix of ice, water, and salt.

The second point, 96 °F, was close to a human body temperature. He also marked 32 °F as the temperature where ice and water meet. Later, the scale was changed so that water freezes at exactly 32 °F and boils at 212 °F. This made it easier to use for everyday temperatures.

Usage

The Fahrenheit scale was the main way to measure temperature in English-speaking countries until the 1960s. After that, most of these countries started using the Celsius scale instead, except for the United States.

Today, Fahrenheit is still used in the United States for everyday things like weather reports, cooking, and freezing food. However, scientists in the U.S. use Celsius and Kelvin for their research.

United States

In the early 1900s, some people thought Fahrenheit was easier to understand for talking about outdoor temperatures in places with mild weather. For example, 100 °F feels like a hot summer day, while 0 °F feels like a cold winter day.

Canada

Canada has laws that support the international system of units, but people there still use Fahrenheit on ovens. Weather reports in Canada are usually in Celsius, but sometimes Fahrenheit is mentioned, especially when broadcasting to places near the U.S. border. Thermometers sold in Canada often show both Celsius and Fahrenheit.

European Union

In the European Union, temperatures for important purposes like health and safety must be given in Kelvins or Celsius. However, Fahrenheit can sometimes be used as an extra measure alongside Celsius.

United Kingdom

Most people in the United Kingdom use Celsius for temperature. But sometimes, Fahrenheit appears in newspapers, especially for higher temperatures, because it can sound more dramatic. For example, "94 °F" might sound hotter than "34 °C."

Unicode representation of symbol

Unicode has a special symbol for the Fahrenheit degree, shown as ℉. This symbol is used for older systems, but Unicode suggests using the degree sign ° followed by the letter F instead. Both ways are treated the same for searching.