How do they actually mesaure temperature that's below zero?

Question

measure * (sorry for the spelling mistake--i know some of the people here are unwilling to answer because of bad spelling haha)

Answer 1

Temperature is actually a measure of the molecular motion of atoms. However, there are several different temperature scales, so something that is 'below zero' may not be zero on another scale. For example, celsius temperatures are scaled using the freezing point of water as zero and the boiling point as 100. The Farenheit scale (most commonly used in the US), is an older one, where "the freezing point of water is 32 degrees and the boiling point is 212 degrees. Zero Fahrenheit was the coldest temperature that the German-born scientist Gabriel Daniel Fahrenheit could create with a mixture of ice and ordinary salt. He invented the mercury thermometer and introduced it and his scale in 1714."
Scientists often use the Kelvin scale, often called 'absolute temperature' "Scientists have determined that the coldest it can get (theoretically) is minus 273.15 degrees Celsius. This temperature has never actually been reached, though scientists have come close. At this temperature scientists believe that molecular motion would stop. You can't get any colder than that."

Answer 2

0 degrees isnt like having 0 apples where you couldnt have negative apples (apple debt). 0 is an arbitrary point that humans created on a thermometer. It makes sense to put 0 at the point where such a common substance (water) changes from a liquid to a solid, but 0 doesnt really exist. The freezing point of water exists but we could have easily made that 100 degrees and the boiling point 200 degrees. 0 does not signify 0 heat. Absolute 0 (or 0 Kelvin) is the theoretical value of the point in which matter collapses on itself. that is when particles have no motion (heat),which causes matter to collapse on itself. Theoretically there is nothing colder than that so that is the true 0.

Answer 3

if you are referring to zero Celsius, or Fahrenheit, these are arbitrary points on a scale so measuring below them is not a problem.
Actual zero (or absolute zero is - minus 273.15 °C - otherwise known as zero Kelvin). it is the total absence of thermal energy. so you cannot measure below it.

To measure below zero Celsius, you take a device that can be calibrated at 2 known points - eg the freezing point of water and the boiling point of water - such as a mercury thermometer. then you divide the scale into as many points as you like (100 in the centigrade or Celsius scale and 180 in the Fahrenheit scale) and mark the scale. Then points below the number zero are colder than zero (or below 32 in Fahrenheit)

Answer 4

Nothing is actually 'cold'. Some things do not have as much heat as others. The thermometers are only a tool to gage how little heat there is. You could invent your own scale if you would like. You could take something that is 100 degrees below zero farenheit and call it 1 degree 'unknownspiritx5' if you would like to.

Answer 5

with the thermometer... it just goes down instead of up. I don't really know anything about this so I'll try to use logic to figure it out. You got the mercury in a tube... you put it somewhere thats just cold enough to get water to freeze and measure the lvl, thats 32F or 0C. Everything colder is down, everything hotter is up. =]

Answer 6

The mercury in the thermometer gets so low that it measures it