Fundamentally, there are 3 temperature measuring scales: Celsius, Fahrenheit, and Kelvin. These temperature scales play an important part in our everyday lives, both domestically and industrially.
Table of Contents
Introduction
Temperature does not only impact our comfort levels but also helps us study the behaviour of matter and energy. In this guide, we shall learn about the 3 primary temperature measuring scales, namely;
- Celsius
- Fahrenheit
- Kelvin
By knowing the history, significance, and practical applications of each of these scales, we can gain a deeper understanding of the role temperature plays in science, engineering, meteorology, and everyday life.
Why Temperature Matters
Temperature is a key factor in various contexts, as it influences many physical, chemical, and biological processes. Whether it is industrial processes, predicting weather patterns, or human comfort, temperature measurements play an essential role.
Definition of Temperature
Temperature is a physical quantity and is among the 7 base quantities in the SI unit. It can be defined as,
“the degree of hotness or coldness of an object or substance.”
It can also be defined as,
“a measure of the average kinetic energy of the particles within a system, where higher temperatures indicate greater kinetic energy of the molecules and vice versa.”
Unit and Nature of Quantity
It is a base and scalar quantity, measured using a specific scale. The SI unit for temperature measurement is kelvin (K).
Role of Temperature
The Temperature in Daily Life
A change in temperature affects our comfort level, health status, and activities in our everyday lives. That is why having an awareness of temperature is needed for making well-informed decisions. For example;
- adjusting the thermostat in our home
- monitoring food temperatures for safety
- checking the weather forecast before planning outdoor activities
Temperature in Science
In scientific research, temperature measurement also plays an important role in studying the behaviour of matter, chemical reactions, and physical phenomena. Additionally, precise temperature control and monitoring are important in laboratories to ensure experimental repeatability and accuracy.
Temperature in Meteorology
In meteorology, we forecast weather conditions as accurately as possible using temperature data. By understanding temperature variations across different regions, meteorologists can predict weather events and climate trends. The temperature gradient in the atmosphere;
- drive wind patterns
- influence cloud formation
- determine the likelihood of precipitation
Temperature in Engineering
In engineering, the effects of temperature must be considered before designing systems, structures, and devices. The reason is that materials can deform or fail due to thermal expansion and contraction. Hence, temperature management becomes important for maintaining structural integrity and performance.
The 3 Temperature Measuring Scales
There are different scales for the measurement of temperature, but the three most commonly used scales are Celsius (C), Fahrenheit (F), and Kelvin (K). Each of these scales is discussed below, along with their origins, defining characteristics, and applications.
Celsius Scale
History and Development
In the 18th century, Swedish astronomer Anders Celsius created the Celsius scale (or the centigrade scale). The scale is based on the physical properties of water. On this scale, 0 ℃ and 100 ℃ represent the freezing point and boiling point, respectively, at standard atmospheric pressure.
Relation to Freezing and Boiling Points of Water
The unique and defining feature of the Celsius scale is its correspondence with the physical characteristics of water. This scale provides a useful and widely accepted framework for measuring temperature because it uses the freezing and boiling points of water as a reference.
Celsius Scale (Definition)
The scale can be defined as “a metric temperature scale where 0 ℃ and 100 ℃ represent the freezing point and boiling point of water, respectively, at standard atmospheric pressure.”
Temperature Conversion
The conversion of temperatures from the Celsius into Fahrenheit and Kelvin scales is made by the following formulas;
Celsius to Fahrenheit
For the conversion of temperature from Celsius (C) to Fahrenheit (F), the following formula is used:
TF = (9/5) × TC + 32
Where,
TC = temperature in Celsius
TF = temperature in Fahrenheit
Celsius to Kelvin
Also, for the conversion of temperature from Celsius (C) to Kelvin (K), the following formula is used:
TK = TC + 273.15
Where,
TC = temperature in Celsius
TK = temperature in Kelvin
Significance of the Celsius Scale
The scale offers a direct and intuitive means to measure temperature, making it accessible to people worldwide. Its association with the physical properties of water also makes it particularly useful for applications involving liquids and gases.
Applications of the Celsius Scale
The scale is usually used in most countries for
- scientific research
- weather forecasts
- laboratory experiments
- everyday temperature measurements
It provides a useful way to express temperature differences and allows for easy comparison between regions and time intervals.
Advantages and Disadvantages of the Celsius Scales
Advantages
- Widely used in meteorological and scientific research.
- Simple to use and comprehend, especially when taking a daily temperature.
- Complies with the characteristics of water, making comparisons and conversions of temperatures easier.
Disadvantages
- Limited range for practical applications.
- Not as precise as the Kelvin scale for research and scientific purposes.
- Can be less familiar to individuals familiarised with the Fahrenheit scale in some regions.
Fahrenheit Scale
History and Development
In the early 18th century, a German physicist named Daniel Gabriel Fahrenheit created the Fahrenheit scale. The scale is based on the physical properties of water. This scale is one of the oldest temperature-measuring scales and is commonly used in the United States and a couple of other countries.
Unlike Celsius (which developed a water-based scale), Fahrenheit at first defined its scale using a mixture of ice, water, and ammonium chloride. Later on, he modified the scale by setting the freezing and boiling points of water at 32 ℉ and 212 ℉, and then dividing them into 180 equal parts.
Relation to Freezing and Boiling Points of Water
Just like the Celsius scale, the Fahrenheit scale is affixed to the freezing and boiling points of water. In comparison to the Celsius, the reference points of the Fahrenheit have different numerical values. This change can lead to confusion when comparing the temperatures on the two scales.
Fahrenheit Scale (Definition)
The scale can be defined as “a non-metric temperature scale where 32 ℉ and 212 ℉ represent the freezing point and boiling point of water, respectively, at standard atmospheric pressure.”
Temperature Conversion
The conversion of temperatures from the Fahrenheit into Celsius and Kelvin scales is made by the following formulas;
Fahrenheit to Celsius
For the conversion of temperature from Celsius (C) to Fahrenheit (F), the following formula is used:
TC = 5/9 × (TF – 32)
Where,
TF = temperature in Fahrenheit
TC = temperature in Celsius
Fahrenheit to Kelvin
For the conversion of temperature from Fahrenheit (F) to Kelvin (K), the following formula is used:
TK = 5/9 × (TF – 32) + 273.15
TK = (5/9) × TF + 255.37
Where,
TF = temperature in Fahrenheit
TK = temperature in Kelvin
Significance of the Fahrenheit Scale
The scale is normally employed in scientific research and international communication. However, the Fahrenheit scale holds cultural significance in countries that primarily use it, such as the United States.
Due to its familiarity and historical legacy, it serves as a suitable reference point for daily temperature measurements and discussions.
Applications of the Fahrenheit Scale
Despite its limited international adoption, the scale remains prevalent in;
- daily use for weather reports
- temperature-sensitive applications
- oven temperatures in cooking recipes
- industrial and everyday settings in the United States and a few other countries
Advantages and Disadvantages of the Fahrenheit Scales
Advantages
- Well-suited for daily applications, including weather reports and cooking.
- Familiarity with the people in countries where it is normally used, including the United States.
- The granular image of temperature changes due to its smaller degree intervals compared to Celsius.
Disadvantages
- Less natural for individuals who are accustomed to the Celsius scale or metric system.
- Limited international adoption leads to confusion when communicating across regions.
- Narrower temperature range, limiting its utility for scientific research involving extreme temperatures.
Kelvin Scale
History and Development
In the mid-19th century, a British physicist named William Thomson (Lord Kelvin) created the Kelvin scale. It has been a preferred unit of temperature measurement since 1954, when the Conference on Weights and Measures (CGPM) adopted it as a standard for temperature.
This absolute temperature scale is based on the Carnot cycle and is named after Lord Kelvin (William Thomson) as the Kelvin scale.
Relation to Freezing and Boiling Points of Water
The freezing and boiling temperatures of water serve as the basis for the Celsius and Fahrenheit scales, whereas the reference point of the Kelvin scale is absolute zero (discussed ahead).
However, to maintain a link with the Celsius scale, the Kelvin scale is designed in such a manner that the freezing point and the boiling point of water are 273.15 K and 373.15 K, respectively. This alignment allows for easy conversion between Celsius and Kelvin temperatures.
Kelvin Scale (Definition)
The scale can be defined as “an SI (International System of Units) temperature scale where 0 K denotes the least possible temperature, known as absolute zero. On this scale, each incremental degree mirrors a 1-degree rise similar to the Celsius scale, but without any inherent offset.”
Temperature Conversion
The conversion of temperatures from the Kelvin into Fahrenheit and Celsius scales is made by the following formulas;
Kelvin to Celsius
For the conversion of temperature from Kelvin (K) to Celsius (C), the following formula is used:
TC = TK – 273.15
Where,
TK = temperature in Kelvin
TC = temperature in Celsius
Kelvin to Fahrenheit
For the conversion of temperature from Kelvin (K) to Fahrenheit (F), the following formula is used:
TF = 9/5 × (TK – 273.15) + 32
TF = (9/5) × TK – 459.67
Where,
TK = temperature in Kelvin
TF = temperature in Fahrenheit
Significance of the Kelvin Scale
The scale offers a globally uniform framework for measuring temperature and is an absolute temperature scale. By defining absolute zero as the least attainable temperature, the Kelvin scale excludes negative temperatures and simplifies calculations that include temperature differentials and energy transfers.
Applications of the Kelvin Scale
The scale is primarily used where extreme temperatures are encountered and precise temperature measurements are necessary, such as:
- astrophysics
- materials science
- scientific research
- engineering applications
- thermodynamics processes
Advantages and Disadvantages of the Kelvin Scale
Advantages
- Absolute nature allows for precise and reliable temperature measurements.
- Simplifies calculations covering gas laws, thermodynamics, and phase transitions.
- Provides a standard reference point for scientific research and engineering applications.
Disadvantages
- Limited familiarity outside of scientific and technical fields.
- Lack of intuitive understanding for individuals accustomed to Celsius or Fahrenheit scales.
- Requires special instruments, such as thermocouples or thermometers calibrated in Kelvin.
Absolute Zero Temperature
Definition of Absolute Zero
The lowest attainable temperature on earth, which theoretically shows the absence of thermal energy, is called absolute zero. At this point, the kinetic energy of particles approaches zero, and hence molecular motion completely ceases. Absolute zero is represented as;
- 0 Kelvin (0 K) on the Kelvin scale
- -273.15 degrees Celsius (−273.15 ℃) on the Celsius scale
- -459.67 degrees Fahrenheit (−459.67 ℉) on the Fahrenheit scale
Significance of Absolute Zero
Absolute zero holds great importance in physics and thermodynamics and acts as an essential reference point for the measurement of temperature and theoretical studies. Some key concepts and phenomena are directly connected to absolute zero. For example;
Ideal Gas Law
According to the ideal gas law equation (PV = nRT), the volume of an ideal gas theoretically becomes zero at an absolute zero temperature.
Entropy
The Third Law of Thermodynamics states that entropy, which is a measure of disorder in a system, approaches zero as the temperature approaches absolute zero.
Quantum Mechanics
Quantum phenomena, such as superconductivity and superfluidity, are only evident at extremely low temperatures.
Thermal Expansion
As materials get closer to absolute zero, molecular motion slows down, and fascinating phenomena like superconductivity and magnetic ordering arise.
Experimental Challenges
It is quite difficult to conduct experiments at temperatures near absolute zero because studying these exotic states of matter and quantum behaviour requires extremely low temperatures.
Even with advanced cryogenic techniques, such as dilution refrigeration and laser cooling, it is challenging to reach and maintain temperatures below a few billionths of a Kelvin (nanokelvins).
Temperature Conversion
Methods and Formulas for Converting Temperatures
Temperature conversion is done across different scales to compare temperature readings. Several formulas exist for this purpose and have been discussed above. However, a generic formula for scale conversion is given below:
Online Tools and Resources
Many online tools and resources are available for temperature conversion. With these tools and resources, individuals can perform temperature conversions accurately and efficiently. For instance;
Temperature Conversion Calculators
These are both online and offline tools that allow users to input a temperature value on one scale and automatically convert it to other scales.
Conversion Charts
These charts offer reference tables for normally used temperature conversions. By using these charts, a user can quickly look up equivalent temperatures between different scales.
Other Temperature Measuring Scales
Apart from the Celsius, Fahrenheit, and Kelvin scales, many other temperature measuring scales have been historically used or are still employed in specialised contexts. For instance (just name a few),
- Rankine (R)
- Réaumur (Ré)
- Newton (N)
Comparison with the Main Temperature Scales
Celsius, Fahrenheit, and Kelvin scales are the most frequently used temperature measuring scales in contemporary contexts. However, the Rankine, Réaumur, and Newton scales offer alternative perspectives on temperature measurement.
These scales can be seen in historical documents, literature, or specialised fields but are normally less relevant in contemporary scientific and engineering practice.
Importance of Temperature Measurement
Temperature influences chemical reactions, the physical properties of materials, biological processes, and environmental conditions. So, regardless of the type of temperature scale used, accurate temperature measurement is necessary for understanding and controlling thermal processes in different fields.
Conclusion
It is important to understand the basics of temperature and different temperature measuring scales, as it is important for a wide range of applications spanning from scientific research to everyday activities. The Celsius, Fahrenheit, and Kelvin scales each present a unique viewpoint on temperature measurement.
Temperature measurement is necessary in various fields, including science, engineering, meteorology, and healthcare. Accurate temperature monitoring enables
- engineers to design efficient systems
- meteorologists to forecast weather patterns
- researchers to study physical and chemical phenomena
- healthcare professionals to diagnose and treat medical conditions effectively
In a nutshell, temperature is more than a numerical value. It is an important aspect of our understanding of the physical world and also a key element in determining our quality of life.
Frequently Asked Questions (FAQs)
What are the 3 temperature measuring scales used for measuring temperature?
The 3 main temperature measuring scales include Celsius, Fahrenheit, and Kelvin. Each scale has its own unique characteristics and applications, making them essential tools for temperature measurement in different fields.
What is the difference between Celsius, Fahrenheit, and Kelvin?
The key difference among these 3 temperature measuring scales is;
- Celsius (C) is created based on the freezing and boiling points of water, where 0 ℃ and 100 ℃ represent the freezing and boiling points, respectively.
- Fahrenheit (F) is commonly used in the United States, where 32 ℉ and 212 ℉ represent the freezing and boiling point of water, respectively.
- Kelvin (K) is an absolute temperature scale, where 0 K represents absolute zero, the lowest possible temperature.
How do I convert temperatures between Celsius, Fahrenheit, and Kelvin?
The following conversion formulas can be used to convert temperatures between Celsius, Fahrenheit, and Kelvin scales;
Celsius into Fahrenheit
TF = (9/5) × TC + 32
Celsius into Kelvin
TK = TC + 273.15
What is absolute zero, and why is it significant?
Absolute zero is the least attainable temperature, where the kinetic energy of particles theoretically ceases. It is denoted as 0 Kelvin (0 K). The equivalents of this temperature value on the Celsius and Fahrenheit scales are -273.15 ℃ and -459.67 ℉ respectively.
Absolute zero is significant because it acts as an important reference point in thermodynamics and physics. It influences phenomena such as the behavior of gases at low temperatures and the concept of entropy.
Are there other temperature scales besides Celsius, Fahrenheit, and Kelvin?
Yes, besides Celsius, Fahrenheit, and Kelvin, other temperature scales have been used historically or in specialised contexts. These include the Rankine (R), Réaumur (Ré), and Newton (N) scales.
What are some practical applications of temperature measurement?
Temperature measurement is essential in various fields, including scientific research, engineering, meteorology, healthcare, and manufacturing. It is used to monitor environmental conditions, control industrial processes, diagnose medical conditions, and ensure product quality and safety.
How does a thermometer work to measure temperature?
A thermometer measures temperature by detecting changes in the physical properties of a substance, such as the expansion or contraction of a liquid or gas, in response to temperature variations. Common types of thermometers include mercury-in-glass thermometers, digital thermometers, and infrared thermometers.
How are temperature standards established and maintained on an international scale?
Organizations such as the International Bureau of Weights and Measures (BIPM) and the International Organization for Standardization (ISO) are responsible for establishing and maintaining temperature standards on an international scale.
These organisations develop and publish standard reference materials, calibration procedures, and measurement protocols to ensure consistency and accuracy in temperature measurement worldwide.
What are the practical applications of the Celsius, Fahrenheit, and Kelvin scales in everyday life and scientific research?
- Celsius is normally used for weather forecasts, everyday temperature measurements, and scientific research.
- Fahrenheit is prevalent in the United States, mainly for weather reporting and cooking.
- Kelvin is mainly used in scientific research, engineering, and thermodynamics due to its absolute nature.