Are Convection and Conduction the Same Form of Heat Transfer?

[Stratosphere]

If heat has three forms ,radiation, convection and conduction, isn't convection another form of conduction? The heat is still moving through the vibration of the atoms convection would just be the pattern at which it is moving in. Another question is how does the heat from the sun radiate to earth?

 

[Feldoh]

Heat doesn't have three forms. Radiation, convection and conduction are ways in which heat is transferred.

As for your second question I think you've already answered it. There are three ways heat is transferred: radiation, convection, and conduction. Well what did you say the sun does? It radiates heat, get it?

 

[mathman]

Convection involves hot fluid motion on a macroscopic scale (air or water currents). Conduction involves molecular vibration transmitting energy by interactions within the material (usually solid). Radiation heat transfer is by photons going from hot body (such as sun) to cooler body (such as earth).

 

[confinement]

The heat is still moving through the vibration of the atoms convection would just be the pattern at which it is moving in.

The pattern makes all the difference. Specifically convection occurs due to fluid velocities which is what is left over after a sort of macroscopic averaging over microscopic movements in a volume that is small compared to the system size but still large compared to the atomic size, while conduction is entirely due to those microscopic movements that convection averages away.

heat doesn't have three forms. Radiation, convection and conduction are ways in which heat is transferred.

To be totally pedantic, radiation, convection, and conduction are three ways of 'doing heat on a thermal system' (compare with 'doing work on a mechanical system').

 

[berkeman]

For a very nice PF Library entry on Heat, click on the underlined "heat" word in the original post.

 

[pallidin]

Just some added thoughts already expressed:

Conduction and convection requires some form of medium; be it air, water, metal, etc...

Radiation is different. A specific physical medium is not required. It can occur in a complete vacuum, for example.

 

[DaleSwanson]

To simplify greatly, in convection atoms move about and take their heat energy with them. In conduction atoms vibrate and collide with other atoms transferring kinetic energy to them, which is what thermal energy really is. In radiation atoms emit photons which travel outward at c until the collide with something else and then add energy to it.

Edit: Thanks mathman, fixed it.

 

[mathman]

To simplify greatly, in conduction atoms move about and take their heat energy with them. In conduction atoms vibrate and collide with other atoms transferring kinetic energy to them, which is what thermal energy really is. In radiation atoms emit photons which travel outward at c until the collide with something else and then add energy to it.

I think you meant to say convention in the first sentence.

 

[Archosaur]

I think you meant to say convention in the first sentence.

I think you meant to say convection. :)

 

[Dadface]

Don't forget evaporation etc.

 

[Redbelly98]

I think you meant to say convention in the first sentence.

I think you meant to say convection. :)

You say that with such conviction.

 

[Archosaur]

You say that with such conviction.

Let's not make this into a huge conniption.

 

[Archosaur]

Hey, that was my 100th post!

Good thing I didn't waste it...

 

[Cantab Morgan]

Don't forget evaporation etc.

Is evaporation a kind of convection? If I threw a dollop of molten lead into a vat of water to warm it up, wouldn't that be convection, too?