Effects of Cooling and Heating in a Cloud Chamber

[HotFurnace]

Good day everybody!
As we have already known the structure and operation of the cloud chamber, can someone explain to me why the cooling is done at the bottom of the chamber and the heating at the top, but not vise versa?? How this affect the function of the cloud chamber?

 

[HotFurnace]

Maybe because they want to reduce the heat flux from the hot side to the cold side when using alcohol as the vapor? So what about water, since it is lighter than air?

 

[darth boozer]

A simple cloud chamber consists of the sealed environment, a warm top plate and a cold bottom plate . It requires a source of liquid alcohol at the warm side of the chamber where the liquid evaporates, forming a vapor that cools as it falls through the gas and condenses on the cold bottom plate. So you actually want the vapor to fall.

 

[HotFurnace]

I don't understand?? The vapor is heavier as it cooler, so the vapor closer to the cold bottom plate is cooler than the vapor layer right next to it, how could it fall down faster than when you reserve the temperature gradient?

 

[HotFurnace]

We always want the supersaturated region as large as possible, so as to improve particles visibility. That's why I asked if reserving the cold plate could help?
I think the cold plate, if some mechanism were implemented to keep it at a appropriate constant temperature regardless of the heat flux flowing through it and are placed on the top, will provide larger supersaturated region than with the cold plate at the bottom. How could I do a calculation to prove (or disprove) it?

 

[darth boozer]

To preserve the tracks, you need the supersaturated region to be as undisturbed as possible. Convection eddies would distort any tracks produced if the heated surface was at the bottom.

 

[davenn]

How could I do a calculation to prove (or disprove) it?

don't need to calculate ... the experiment would be easy to set up and you would observe the
problem as stated in the quote below

To preserve the tracks, you need the supersaturated region to be as undisturbed as possible. Convection eddies would distort any tracks produced if the heated surface was at the bottom.

exactly

 

[HotFurnace]

Thanks for all replies! I will do a experiment to confirm this!