Temperature is measure how hot or cold other is, such together the external air temperature, your body temperature, temperature the water because that cooking, boiling, washing, etc.

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So, is that cold or hot when the temperature projection says it will certainly be 5 degrees or it will certainly be 30 degrees? What temperature go water frozen at? Or boil at? What temperature is comfortable for her living room?


Using the modern-day Celsius system of temperature measurement, we can quickly determine how hot or cold the is. That was additionally known as Centigrade. This is because it is based on the freezing and also boiling point out of water with 100 degrees between those temperatures.

The main SI unit of temperature is the kelvin, which measures absolute temperatures. But, because that our day-to-day usage, we usage Celsius i beg your pardon is directly related come kelvins. That is collection so that pure water freezes in ~ zero levels Celsius and boils at one hundred degrees Celsius.

This is a very easy mechanism to learn as these two marker points room so simple to remember:

Freezing in ~ 0 °C

Boiling in ~ 100 °C

And v 100 degrees in between those points, we can specify temperatures utilizing 1 or 2 digit positive numbers. As soon as the temperature is negative, i.e. Listed below 0 °C, climate we understand that the is therefore cold that water will certainly freeze. Water will constantly be ice below 0 °C, liquid from 1 come 99 °C, and steam from 100 °C upwards.

Here is a table mirroring some guidelines regarding Celsius temperatures:

Temperature °CWhat could be at this temperatureHow the feelsOther clues of interest

-30 (that is 30 degrees listed below zero)

Ice, freezer

Very cold if you are external in this temperature, unbearable come most




Very cold still yet bearable if in lots of heat clothes



Water freezes, ice cream melts


Typical coldest average temperature because that UK in winter




Water has its the smallest volume at this temperature*





20Room indoorsWarm
25Warm roomWarm to hot
Typical maximum temperature for British summer
30Hot dayFeeling hotTypical temperature because that hotter countries


Body temperature

Very hot

This is the average human being body temperature

40Washing device setting for clothing for regular washVery hot
If you are exterior in this temperature you will certainly feel hot, but much more so if humidity is high.If your inner body temperature get this level you space in hazard of death.
50Extremely hotNot many places acquire this high in temperature, and this warmth you would require to find shade, drink water and also stay cool.
60Washing maker setting for warm wash
Too hot to live inMost bacteria dice at this temperature
90Washing machine setting because that hottest washToo warm to live inHumans cannot survive such high temperatures
100Water boils in the kettle

Water turns to steam
1000Lava from a volcano

1535Melting point of iron


15 000 000

Core of the Sun

*Note the water broadens as the temperature increases above 4 degrees, and also as that goes colder listed below 4 degrees. Its volume will be at its smallest at 4 °C. This is crucial to remember as soon as freezing water in the icebox or freezer, together the water will undoubtedly increase in volume as it freezes, and also the cooler it gets, the enlarge the ice cream gets. For this reason remember no to placed water into a party that will be in the freezer for an ext than a minute or so, as the water inside will certainly expand and break the bottle.

If you need to work in warm conditions, here are guidelines for rest durations needed:

TemperatureRest period (per hour that work)

30 come 32 ºC

10 minutes

32 to 35 ºC

15 minutes

more than 35 ºC

at the very least 30 minutes

Remember that once you watch a weather projection on TV, in a newspaper or ~ above the radio, that anything native 20 degrees upwards is going to be warm, over 25 degrees is hot, above 30 degrees is an extremely hot. Listed below 20 is cool, listed below 10 degrees is cold, and below zero degrees way that it will be icy outside as the water will freeze and it will certainly feel really cold outside.

Kelvin (for the an ext scientific amongst us)

The kelvin (symbol: K) is the SI unit that temperature, and also is one of the 7 SI base units. The is characterized by two facts: zero kelvin is absolute zero (when molecular activity stops), and one kelvin is the portion 1/273.16 that the thermodynamic temperature the the triple point of water (0.01 °C). The Celsius temperature scale is now defined in terms of the kelvin.

The kelvin is called after the brothers physicist and engineer william Thomson, 1st Baron Kelvin. For this reason we have another metric unit called after a brother person. Most metric units are not foreign at all, unequal °F i m sorry is Foreign! The level Celsius (°C) is called after the swedish astronomer Anders Celsius (1701–1744) yet as the is now characterized in terms of the kelvin, it is an ext British 보다 Fahrenheit, called after a German scientist.

The indigenous kelvin together an SI unit is effectively written through a lowercase k (unless in ~ the start of a sentence), and also is never ever preceded through the words level or degrees, or the symbol °, uneven Celsius. This is because Celsius is a range of measurement, vice versa, the kelvin is a unit that measurement.

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The freezing point of water, together we recognize from what we review above, is 0 °C, and 0 °C = 273.15 K. For every increase by 1 °C the temperature additionally increases by 1 K. For this reason 0 K = -273.15 °C, 100 K = -173.15 °C, 273.15 K = 0 °C, and the boiling point of water is 373.15 K (100 °C).