Celsius

We use this scale to measure heat.

It tells us if it is hot or cold.

Water freezes at 0 degrees. Water boils at 100 degrees. This scale is named after a man named Anders Celsius.

He lived a long time ago. At first, his scale was backward. He used 0 for boiling water. He used 100 for freezing water.

Later, people flipped the numbers. Now, 0 is for freezing. This helps us know the weather.

Most lands use this scale. The United States does not use it.

How do we measure heat? Most people use the Celsius scale. It tells us how hot or cold something is.

This scale is named after Anders Celsius. He was a scientist from Sweden. He lived a long time ago. In 1742, he made a new scale. But his scale was backward! He used 0 for boiling water. He used 100 for freezing water.

Later, other people flipped the numbers. Now, 0 is for freezing water. 100 is for boiling water. This makes it much easier to use. For a long time, people called it the centigrade scale. The word centigrade means "one hundred steps." In 1948, they changed the name to Celsius. This was to honor the man who started it.

Most countries in the world use this scale. The United States is one place that does not. They use a different scale called Fahrenheit.

Scientists also use the Kelvin scale. The Kelvin scale is very close to Celsius. It is used to measure very deep cold.

Have you ever wondered how we measure heat? Most people use the degree Celsius to describe temperature. It is a very important tool for science and daily life. This scale tells us how hot or cold something is.

It is one of two scales used in the International System of Units. The other scale is called Kelvin. Most countries in the world use Celsius every single day. Only a few places, like the United States and Liberia, use the Fahrenheit scale instead.

The Celsius scale works by using the properties of water. For a long time, the scale used two main points. The first point was the freezing point of water. The second point was the boiling point of water. These points were measured at one standard atmosphere of pressure. At this pressure, water freezes at 0 degrees Celsius. It boils at 100 degrees Celsius.

This makes it easy to remember the steps of the scale.

The history of this scale is quite surprising. A Swedish astronomer named Anders Celsius first proposed it in 1742. However, his original version was actually backward! He set 0 degrees for boiling water and 100 degrees for freezing water.

In 1743, a French physicist named Jean-Pierre Christin flipped the scale. Later, a botanist named Carl Linnaeus also used the reversed version. By the 19th century, the scale we use today became the standard.

Many people used to call this the centigrade scale. The name comes from Latin words meaning "one hundred steps." In 1948, experts officially renamed it to honor Anders Celsius. They did this to avoid confusion with other measurements.

Since 2007, scientists have defined the scale using the Kelvin scale. This helps keep measurements very precise for science. Even though the name changed, many people still use the word centigrade informally.

You can see how Celsius connects to your own world. For example, a comfortable room is about 20 degrees Celsius. The average temperature of a human body is about 37 degrees Celsius. If you see a temperature of 0 degrees, you know ice might form.

If the temperature hits 100 degrees, water will start to boil. It is a simple way to understand the world around us.

The degree Celsius is a fundamental unit used to measure temperature. It is part of the Celsius temperature scale, which is one of two scales used in the International System of Units (SI). The other closely related scale is the Kelvin scale. The Celsius scale is used by most countries across the globe. However, some places like the United States, Liberia, and certain island territories still use the Fahrenheit scale.

This scale is vital for science, weather reporting, and daily life because it provides a standardized way to describe heat.

Historically, the scale was defined by the physical properties of water. For much of the 19th and early 20th centuries, scientists used the freezing and boiling points of water. These points were measured at one standard atmosphere of pressure. Under these specific conditions, water freezes at 0 °C and boils at 100 °C. This created a system of 100 equal steps between the two states.

This method allowed for consistent measurements in laboratories and homes.

Between 1954 and 2019, the definition of the scale became more complex and precise. Scientists moved away from simple boiling and freezing points. Instead, they used the triple point of water to define the scale. The triple point is a specific condition where water can exist as a solid, liquid, and gas at once. In 2005, they even specified the exact isotopic composition of the water used. Since 2007, the Celsius scale has been defined in terms of the Kelvin scale. This ensures that the magnitude of one degree Celsius is exactly equal to one Kelvin.

The history of the scale involves several different scientists and surprising changes. In 1742, a Swedish astronomer named Anders Celsius proposed the first version. Interestingly, his original scale was reversed from the one we use today. He set 0 °C as the boiling point and 100 °C as the freezing point.

In 1743, a French physicist named Jean-Pierre Christin inverted the scale. Some believe Christin invented this version independently, while others say he simply flipped Celsius's work. Later, in 1744, the botanist Carl Linnaeus also used a reversed scale for his greenhouses.

For many years, the scale was commonly known as the centigrade scale. The name comes from Latin words meaning "one hundred steps." In 1948, the International Committee for Weights and Measures officially renamed it to honor Anders Celsius. They did this to prevent confusion with the term "gradian," which refers to angular measurements in some languages. While "Celsius" is the standard in scientific work, the term "centigrade" is still used informally in some English and French-speaking regions. In Australia, weather reports switched exclusively to Celsius in 1972. The BBC in the United Kingdom also switched from "centigrade" to "Celsius" in 1985.

We can see the scale in action by looking at common temperatures. For instance, the average normal human body temperature is about 37.0 °C. A common room temperature is often around 20 °C. At the extreme low end, absolute zero is defined as exactly -273.15 °C.

This is the lowest possible temperature. On the high end, the boiling point of liquid nitrogen is -195.8 °C. These numbers help scientists and engineers communicate exact thermal states across the world.

It is important to understand how the Celsius scale relates to other systems. While it is used for specific temperatures, it can also express temperature intervals. An interval is the difference between two temperatures, such as a change of 40 °C. The scale follows an interval system rather than a ratio system. This means that an object at 20 °C does not have twice the thermal energy of an object at 10 °C. Because the scale is relative and not absolute, 0 °C is not the lowest possible value. In professional science, the Celsius scale and the Kelvin scale are often used together to provide highly accurate data.