Temperature is measure how warm or cold miscellaneous is, such together the outside air temperature, her body temperature, temperature that water because that cooking, boiling, washing, etc.

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So, is the cold or warm when the temperature forecast says it will be 5 degrees or it will certainly be 30 degrees? What temperature walk 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 conveniently determine how warm or cold it is. That was additionally known together Centigrade. This is because it is based on the freezing and boiling clues of water through 100 degrees in between those temperatures.

The key SI unit that temperature is the kelvin, which actions absolute temperatures. But, because that our everyday usage, we use Celsius i beg your pardon is directly related come kelvins. The is collection so the pure water freezes at zero levels Celsius and boils at one hundred levels Celsius.

This is a an extremely easy system to discover as these 2 marker points are so simple to remember:

Freezing at 0 °C

Boiling at 100 °C

And v 100 degrees in between those points, we deserve to specify temperatures using 1 or 2 digit hopeful numbers. As soon as the temperature is negative, i.e. Listed below 0 °C, climate we understand that the is for this reason cold the water will freeze. Water will constantly be ice listed below 0 °C, liquid from 1 come 99 °C, and steam from 100 °C upwards.

Here is a table showing some guidelines as to Celsius temperatures:

Temperature °CWhat can be at this temperatureHow it feelsOther clues of interest

-30 (that is 30 degrees listed below zero)

Ice, freezer

Very cold if girlfriend are outside in this temperature, unbearable come most




Very cold still yet bearable if in too many of warm clothes



Water freezes, ice cream melts


Typical coldest mean temperature for UK in winter




Water has its smallest volume in ~ this temperature*





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


Body temperature

Very hot

This is the average person body temperature

40Washing machine setting for clothing for typical washVery hot
If girlfriend are exterior in this temperature you will feel hot, but an ext so if humidity is high.If your inner body temperature will this level you room in danger of death.
50Extremely hotNot countless places acquire this high in temperature, and also this warm you would need to discover shade, drink water and also stay cool.
60Washing maker setting for hot wash
Too warm to live inMost bacteria die at this temperature
90Washing device setting for hottest washToo hot to live inHumans cannot endure such high temperatures
100Water boils in the kettle

Water turns to steam
1000Lava native a volcano

1535Melting suggest of iron


15 000 000

Core that the Sun

*Note the water expands as that is temperature increases above 4 degrees, and as that goes colder below 4 degrees. That is volume will certainly be at its the smallest at 4 °C. This is vital to remember as soon as freezing water in the icebox or freezer, as the water will certainly undoubtedly increase in volume together it freezes, and the cooler it gets, the enlarge the ice gets. For this reason remember not to put water into a party that will be in the freezer for an ext than a minute or so, together the water inside will expand and also break the bottle.

If you have to work in hot conditions, right here are guidelines because that rest durations needed:

TemperatureRest period (per hour of work)

30 to 32 ºC

10 minutes

32 come 35 ºC

15 minutes

more than 35 ºC

at least 30 minutes

Remember that as soon as you watch a weather projection on TV, in a newspaper or ~ above the radio, the anything from 20 degrees upwards is going to be warm, above 25 degrees is hot, above 30 degrees is very hot. Below 20 is cool, listed below 10 degrees is cold, and also below zero degrees method that it will certainly be icy outside as the water will certainly freeze and also it will certainly feel very cold outside.

Kelvin (for the an ext scientific amongst us)

The kelvin (symbol: K) is the SI unit of temperature, and is among the seven SI basic units. It is defined by two facts: zero kelvin is absolute zero (when molecular motion stops), and also one kelvin is the fraction 1/273.16 of the thermodynamic temperature the the triple suggest of water (0.01 °C). The Celsius temperature scale is now characterized in terms of the kelvin.

The kelvin is named after the brother physicist and engineer wilhelm Thomson, first Baron Kelvin. Thus we have one more metric unit called after a british person. Many metric units are not foreign at all, unequal °F i m sorry is Foreign! The degree Celsius (°C) is called after the swedish astronomer Anders Celsius (1701–1744) however as that is now characterized in terms of the kelvin, it is much more British than Fahrenheit, called after a German scientist.

The indigenous kelvin together an SI unit is correctly written v a lowercase k (unless in ~ the start of a sentence), and is never ever preceded by the words degree or degrees, or the symbol °, uneven Celsius. This is because Celsius is a scale of measurement, whereas the kelvin is a unit that measurement.

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The freezing point of water, as we understand from what we read above, is 0 °C, and also 0 °C = 273.15 K. For every boost by 1 °C the temperature likewise increases through 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).