Question: What the Hell IS temperature anyway?

[wkrepelin]

it's all in the title. what is temperature? I know that it's "hot" today but, I mean, what are thermometers measuring?

EDIT: Ah, I see bolding the titles doesn't work around her, eh? Damn you internet gerbils!

EDIT2: Okay, so people seem to be saying that it's little molecules and stuff moving. So, does that mean if I run along side them and go the same speed that I heat up or do they seem cold then? If we're going the same speed are they absolute zero or do we both have to be stopped for that to happen?

 

[Dags90]

Average kinetic energy.

 

[Toranilor]

I think it's an arbitrary scale to measure, you know, how hot something is.

If you want to get techincal, I'm fairly sure that the kevlin scale measures the amount of energy transferred into the device. (Hot stuff vibrates faster on an atomic level, and so transferres more energy and at a faster rate.)

 

[wkrepelin]

Average kinetic energy.

...O.O... moar plz

 

[The_Healer]

You really want to go into this? You really do?

Well go read a physics text book.

In short, it is measuring the amount of vibrations of atoms in a substance. This vibration becomes smaller in "cold" temperatures and greater in "hot" temperatures.

 

[2012 Wont Happen]

The amount of energy in the air molecules. If there is no energy in the air molecules, and they are at a standstill, that is called 0 kelvin (absolute zero) and nothing can happen at all. There is nowhere that is 0 kelvin. Even in space, there is a small amount of energy.

So, a unit of energy.

 

[wkrepelin]

You really want to go into this? You really do?

Well go read a physics text book.

In short, it is measuring the amount of vibrations of atoms in a substance. This vibration becomes smaller in "cold" temperatures and greater in "hot" temperatures.

So, what amount of vibration is a degree celsius?

 

[Dags90]

Consider H20. When it's ice, most of the energy has been transferred from it. The molecules don't move much and eventually form a crystal lattice by hydrogen bonding with each other. These atoms vibrate, but they're bonded into a fair immobile lattice structure, like bricks without mortar. As the system absorbs heat, the vibrations increase. Eventually these vibrations are strong enough to start breaking the weak hydrogen bonds and we have liquid water. If this water is continuously heated, it will start to boil at 100C(Standard Pressure).

The average part is most important for understanding phase changes. At 0C, not all of the ice has enough energy to become water at once. Some of it has enough energy, some of it doesn't but the average energy is just barely melted. This is also why water evaporates at temperature lower than boiling. While the average energy is lower than that required to become gas, some particles do have enough energy to become gas.

I haven't really taken any physics classes, so my knowledge is limited to how it applies to chemistry.

 

[mooncalf]

A degree celsius is equal to one kelvin or 1.8 degrees farenheit. I'm not sure how to meaningfully express what "amount of vibration" a degree celsius is, perhaps look into that yourself and get back to us with the answer?

 

[RUINER ACTUAL]

If you want to get on a molecular level, the friction caused by radiation from the Sun between gas molecules, measured in a way we can understand.

That's my idea.

 

[HK_01]

The movement of particles. The faster they move, the warmer it is.

 

[Spinozaad]

Magic, just like magnets.

 

[xdgt]

Well, like people have mentioned temperature is kinetic energy on inter molecular level, 0 kelvin is absolute zero when the molecules don't move at all, the higher the temperature the faster the molecules move on average, there is the freezing point when something solid (molecules maintaining a formation and basically sticking together - like a crowd standing) becomes liquid (molecules move between each other but still maintain some connection between themselves - like a person moving through a crowd, except almost every person in the crowd is moving through the crowd) or vice versa and then there is the boiling point when something liquid becomes gas (molecules maintain minimal connection between each other and basically act almost separately of each other - like if the people in the crowd suddenly all went home, some would spread through the city, some would stay in the same area) or vice versa. Then there is 0 Celsius, it is water's freezing point and 100 Celsius is water's boiling point, 1 degree Celsius would be one percent of the difference between the energy water has at its freezing point and the energy it has at its boiling point (the same energy as 1 degree Kelvin).

 

[wkrepelin]

so, why does wind feel cool instead of hot?

 

[xdgt]

so, why does wind feel cool instead of hot?

Because temperature is the movement on molecular level not on human sized level, so the oxygen molecules might be not moving fast relatively to each other but are moving fast relatively to you. Kind of how you are not moving relatively to your apartment but moving at huge speed relatively to the sun.

 

[StBishop]

A degree celsius is equal to one kelvin or 1.8 degrees farenheit. I'm not sure how to meaningfully express what "amount of vibration" a degree celsius is, perhaps look into that yourself and get back to us with the answer?

Not quite.

The Celcius scale lines up with the Kelvin scale but 1C is equal to 274K.

Different perspective 0 degrees Kelvin = -273 Degrees Celcius.

 

[Trivun]

The amount of energy in the air molecules. If there is no energy in the air molecules, and they are at a standstill, that is called 0 kelvin (absolute zero) and nothing can happen at all. There is nowhere that is 0 kelvin. Even in space, there is a small amount of energy.

So, a unit of energy.

What if you stick a bell jar, having had all the air sucked out, in a room that's completely dark (and I mean absolutely zero light getting in, and completely sealed)? Since heat energy can be transferred in three different ways, two of which (convection and conduction) require particles to be present. In a bell jar, no particles are present so the only energy within would be transferred by radiation, the third way. But in a sealed pitch black room, there would be no light, so no heat energy could be transferred by radiation. So surely then, the temperature inside the bell jar would be absolute zero?

 

[Anarchemitis]

so, why does wind feel cool instead of hot?

While the air may have the same temperature as a given room (20C) and be taking heat away from your body casually (sweat, or otherwise passive body heat exhaust -like breathing and so on), the process is accelerated by the air moving, giving more air volume per unit of time that is exposed to the surface of your body, allowing more energy to be transferred from your body to the air.
This faster transfer of energy from hot object (you) to cool object (air) is the loss of heat energy, but accelerated, making you feel colder.

 

[Dags90]

so, why does wind feel cool instead of hot?

If you've ever used a blow dryer, you know that wind can feel hot as well. Wind one of the ways energy is transferred, the transfer can lead to an increase in heat (the hair dryer) or a decrease in heat (low pressure system winds).

Another factor is evaporative cooling, this is how sweating works. You cover yourself in a thin layer of water, which absorbs energy from its environment (you and the air). This water then evaporates off you, taking with it some of your excess energy (temperature). Wind speeds this process up by increasing the environmental energy.

So surely then, the temperature inside the bell jar would be absolute zero?

Perfect vacuums have a temperature of absolute zero, correct. They're not really feasible, however. More forms of radiation energy exist other than visible light, in fact visible light is but a small part of the large electromagnetic spectrum.