This entry measures temperature in Fahrenheit. For Celsius, click here.

Temperature is used when we want to measure how hot or cold something is. We call the unit Fahrenheit. At a temperature of $32$ °F, water freezes into ice. At a temperature of $212$ °F, water starts boiling. The temperature in your body is about $99$ °F. When Fahrenheit originated, it was intended that $100$ °F should be based on a human’s average body temperature. Unfortunately, body temperature is not a reliable constant temperature and average body temperature has dropped since then.

You might have several thermometers at home: One showing how many degrees are outside, and one to determine your fever. Before you leave your home, it is often wise to check the degrees outside, in order for you to choose the correct outfit—not too warm and not too cold.

In the summer, it is much hotter than in the winter. Nice summer days often have a temperature of about $90$ °F, while in the winter, it might be as cold as $10$ °F.

Another example is the difference between your refrigerator and your freezer. It feels much colder in the freezer than in the refrigerator. That’s because it is $-4$ °F in the freezer and $40$ °F in the refrigerator.

There are several types of thermometers. Some are digital and display the temperature on a screen. Others consist of a glass cylinder with a range of numbers on the side.

Often, the range of numbers goes form $-60$ °F to $120$ °F, where the temperatures below $32$ °F are colored blue, and the temperatures above $32$ °F are colored red.

In the bottom of the thermometer made up of a glass cylinder, there is a small ball with mercury in it. The mercury reacts to the temperature outside and expands as the temperature rises. When the mercury expands, it creeps upwards in the cylinder. Where the mercury stops, you can find the temperature.