Temperature is measuring how warm or cold something is, such as 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 be 5 degrees or it will certainly be 30 degrees? What temperature go water frozen at? Or cook at? What temperature is comfortable for her living room?


Using the modern Celsius mechanism of temperature measurement, we can quickly determine how hot or cold it is. That was also known as Centigrade. This is because it is based on the freezing and also boiling points of water v 100 degrees between those temperatures.

The main SI unit of temperature is the kelvin, which measures absolute temperatures. But, for our day-to-day usage, we use Celsius which is straight related come kelvins. That is set so that pure water freezes at zero degrees Celsius and boils at one hundred levels Celsius.

This is a very easy system to find out as these 2 marker points space so easy to remember:

Freezing at 0 °C

Boiling at 100 °C

And with 100 degrees in between those points, we have the right to specify temperatures using 1 or 2 digit hopeful numbers. When the temperature is negative, i.e. Below 0 °C, climate we know that that is for this reason cold that water will freeze. Water will always be ice below 0 °C, fluid from 1 come 99 °C, and heavy steam from 100 °C upwards.

Here is a table mirroring some guidelines regarding Celsius temperatures:

Temperature °CWhat can be in ~ this temperatureHow the feelsOther points of interest

-30 (that is 30 degrees below zero)

Ice, freezer

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




Very cold still but bearable if in lots of warmth clothes



Water freezes, ice cream melts


Typical coldest average temperature for UK in winter




Water has its smallest volume in ~ this temperature*





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


Body temperature

Very hot

This is the average person body temperature

40Washing maker setting for clothes for typical washVery hot
If friend are external 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 room in peril of death.
50Extremely hotNot many places obtain this high in temperature, and this warmth you would need to find shade, drink water and also stay cool.
60Washing an equipment setting for warm wash
Too warm to live inMost bacteria die at this temperature
90Washing device setting for hottest washToo hot to live inHumans cannot make it through such high temperatures
100Water boils in the kettle

Water turns to steam
1000Lava from a volcano

1535Melting point of iron


15 000 000

Core that the Sun

*Note that water increases as that temperature increases above 4 degrees, and as it goes colder listed below 4 degrees. The volume will be at its smallest at 4 °C. This is essential to remember when freezing water in the icebox or freezer, together the water will undoubtedly increase in volume as it freezes, and also the chillier it gets, the bigger the ice gets. Therefore remember not to placed water right into a bottle that will be in the freezer for an ext than a minute or so, as the water inside will certainly expand and also break the bottle.

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

TemperatureRest period (per hour the work)

30 to 32 ºC

10 minutes

32 to 35 ºC

15 minutes

more 보다 35 ºC

at the very least 30 minutes

Remember that once you view a weather projection on TV, in a newspaper or top top the radio, that anything native 20 degrees upwards is walking to be warm, over 25 degrees is hot, over 30 degrees is an extremely hot. Below 20 is cool, 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 it will feel really cold outside.

Kelvin (for the an ext scientific amongst us)

The kelvin (symbol: K) is the SI unit of temperature, and also is one of the seven SI base units. That is identified by 2 facts: zero kelvin is pure zero (when molecular motion stops), and one kelvin is the fraction 1/273.16 of the thermodynamic temperature the the triple allude of water (0.01 °C). The Celsius temperature scale is now defined in regards to the kelvin.

The kelvin is called after the brothers physicist and engineer wilhelm Thomson, 1st Baron Kelvin. For this reason we have one more metric unit called after a brothers person. Most metric units space not foreign at all, unequal °F which is Foreign! The degree Celsius (°C) is called after the swedish astronomer Anders Celsius (1701–1744) however as it is now defined in regards to the kelvin, the is much more British 보다 Fahrenheit, named after a German scientist.

The indigenous kelvin together an SI unit is properly written through a small letter k (unless in ~ the beginning of a sentence), and is never preceded through the words level or degrees, or the symbol °, unlike Celsius. This is because Celsius is a scale of measurement, vice versa, the kelvin is a unit of measurement.

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