| Celsius (°C) | The Celsius (°C) is a unit of temperature commonly used in most countries around the world.
It is based on the freezing point of water at 0°C and the boiling point at
100°C, under standard atmospheric pressure. The Celsius scale is widely used
in science, weather forecasting and daily life to measure temperature.
Conversions:
- °C = (°F - 32) x 5/9
- °C = K - 273.15
- °C = °R x 5/9 - 273.15
- °C = °Ré x 5/4
Features:
- Freezing Point of Water: 0°C (under standard atmospheric pressure)
- Boiling Point of Water: 100°C (under standard atmospheric pressure)
Common Uses:
-
Weather Forecasting
Celsius is used globally (except in the U.S.) to report and predict air temperatures, helping people plan daily activities and prepare for extreme weather conditions.
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Cooking
In kitchens, Celsius is used for setting oven temperatures, ensuring food safety (e.g., cooking meats to specific temperatures) and following recipes, particularly in baking and candy-making.
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Scientific Research
Celsius is the standard for measuring temperature in scientific experiments, especially in fields like chemistry, biology and climate studies, ensuring consistent global communication of results.
| °C = (°F - 32) x 5/9 °C = K - 273.15 °C = °R x 5/9 - 273.15 °C = °Ré x 5/4 |
| Fahrenheit (°F) | The Fahrenheit (°F) scale is a temperature scale primarily used in the United States and its territories.
It is based on the freezing and boiling points of water, but with different reference
points than the Celsius scale.
Conversions:
- °F = (°C x 9/5) + 32
- °F = (K - 273.15) x 9/5 + 32
- °F = °R - 459.67
- °F = (°Ré x 9/4) + 32
Features:
- Freezing Point of Water: 32°F (under standard atmospheric pressure)
- Boiling Point of Water: 212°F (under standard atmospheric pressure)
Common Uses:
-
Weather Forecasting
Fahrenheit is primarily used in the United States for reporting daily temperatures, helping people dress appropriately and plan activities.
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Home Heating and Cooling
Thermostats in U.S. homes often display temperature in Fahrenheit to control indoor heating and air conditioning systems.
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Cooking
Recipes, especially in the U.S., often provide oven temperatures in Fahrenheit for baking, roasting and grilling.
| °F = (°C x 9/5) + 32 °F = (K - 273.15) x 9/5 + 32 °F = °R - 459.67 °F = (°Ré x 9/4) + 32 |
| Kelvin (K) | The Kelvin (K) is the SI (International System of Units) unit for temperature. It is an absolute
scale, meaning it starts at absolute zero, the theoretical point where all
molecular motion ceases.
Conversions:
- K = °C + 273.15
- K = (°F - 32) x 5/9 + 273.15
- K = °R x 5/9
- K = (°Ré x 5/4) + 273.15
Features:
- Absolute Zero: 0 K, equivalent to -273.15°C
- No Negative Values: Kelvin temperatures are always positive because they are measured from absolute zero.
- Scale: Each increment of 1 K is equivalent to 1°C, so the size of the degree is the same as in Celsius.
Common Uses:
-
Scientific Research
Kelvin is widely used in scientific fields like physics, chemistry and astronomy, where precise and absolute temperature measurements are needed.
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Temperature Measurement
Kelvin is used in thermodynamics, particularly when dealing with gas laws and energy calculations.
| K = °C + 273.15 K = (°F - 32) x 5/9 + 273.15 K = °R x 5/9 K = (°Ré x 5/4) + 273.15 |
| Rankine (°R) | The Rankine (°R) is a temperature scale used primarily in thermodynamics, particularly in
engineering and the U.S. for certain scientific applications. It is an absolute
scale like Kelvin, but uses Fahrenheit degrees instead of Celsius degrees.
Conversions:
- °R = (°C + 273.15) x 9/5
- °R = °F + 459.67
- °R = K x 9/5
- °R = (°Ré x 9/4) + 491.67
Features:
- Absolute Zero: 0°R, equivalent to -459.67°F.
- Zero Point: 0°R represents absolute zero, the temperature at which molecular motion theoretically stops.
- Scale: The size of the degree is the same as Fahrenheit, meaning each increment of 1°R is equivalent to a 1°F change.
Common Uses:
-
Thermodynamic Systems
In systems involving heat engines, particularly steam turbines and refrigeration cycles, the Rankine scale is often used to express temperatures in processes such as the Rankine cycle (the thermodynamic cycle used by steam engines).
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Energy Calculations
It helps in calculating the work and efficiency of thermal systems, where temperature differences between heat sources and heat sinks are critical.
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Power Plant Engineering
It is used to measure and calculate steam temperatures and pressures in power plants for efficient energy conversion.
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Engineering and Design
Engineers use the Rankine scale when designing and analyzing systems that rely on heat exchange and energy conversion, such as HVAC systems, turbines, and jet engines.
| °R = (°C + 273.15) x 9/5 °R = °F + 459.67 °R = K x 9/5 °R = (°Ré x 9/4) + 491.67 |
| Réaumur (°Ré) | The Réaumur (°Ré) is a historical temperature scale, mostly used in Europe and some parts of the
world until the 19th century. It is based on the freezing and boiling points of
water, similar to Celsius, but with a different scale division.
Conversions:
- °Ré = °C x 4/5
- °Ré = (°F - 32) x 4/9
- °Ré = (K - 273.15) x 4/5
- °Ré = (°R - 491.67) x 4/9
Features:
- Freezing Point of Water: 0°Ré (at standard atmospheric pressure)
- Boiling Point of Water: 80°Ré (at standard atmospheric pressure)
- Scale: The scale is divided into 80 equal intervals between the freezing and boiling points of water, compared to 100 in Celsius.
Common Uses:
-
Historical Use:
Once used in Europe for scientific and industrial purposes, but has largely been replaced by Celsius.
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Cooking and Industry
It was used for certain industrial processes and in some regions for measuring temperature in cooking.
| °Ré = °C x 4/5 °Ré = (°F - 32) x 4/9 °Ré = (K - 273.15) x 4/5 °Ré = (°R - 491.67) x 4/9 |