 # Three Big Temperature Scales

Since we're going to be talking about heat, temperatures, and energy, we wanted to introduce you to how temperature is measured. The big three are Fahrenheit, Celsius and Kelvin. Even though scientists may use only a few scales to measure temperature, there are dozens of types of devices that measure temperatures. All of these devices are called thermometers because they measure temperature. There are thermometers to measure your body temperature, the temperature in your oven, and even the temperature of liquid oxygen.

# Fahrenheit is the Classic

Fahrenheit is the classic English system of measuring temperatures. Water freezes at 32 degrees Fahrenheit and boils at 212 degrees. The scale was created by Gabriel Daniel Fahrenheit in 1724 and divides the difference between the boiling point and freezing point of water into 180 equal degrees. You will probably be asked to convert temperatures back and forth from Fahrenheit to Celsius. Here's the formula: (Fahrenheit-32)*5/9=Celsius.

# Celsius Based on Water

Celsius is the modern system of measuring temperature. It fits in with much of the metric system and has nice round numbers. In Celsius, we call the freezing point of water 0 degrees Celsius, and the boiling point 100 degrees Celsius. Then the scale is divided into 100 equal degrees between those two points. The scale used to be known as centigrade but the name was changed several years ago. Both Celsius and Fahrenheit are used when discussing our day-to-day weather temperatures. Celsius degrees are larger than Fahrenheit degrees.

# Kelvin to Absolute Zero

Kelvin is an important scale used in most of science. The big difference is that it is based on a single point (absolute zero) which is given a value of 0 degrees. From there, the scale increases by degrees that are the same size as Celsius degrees. It is a scale that is based on energy content, rather than on arbitrary temperature values like the other two scale (based on water). Water freezes at the value 273.15 and boils at 373.15 Kelvin. The word "Kelvin" comes from Lord Kelvin, who did a lot of work with temperatures.   Or search the sites for a specific topic. James Webb Telescope Testing (NASA/MSFC Video) Physics4Kids: Laws of Thermodynamics
Chem4Kids: Reaction Thermodynamics
Chem4Kids: Changing States of Matter
Chem4Kids: Catalysts
Biology4Kids: System Regulation
Biology4Kids: Endocrine System
Geography4Kids: Earth Energy
Geography4Kids: Air Temperature
Geography4Kids: Emittance
Cosmos4Kids: Star Classes
Cosmos4Kids: The Sun

Physics4Kids Sections

Rader's Network of Science and Math Sites