So I get that when the VP is equal to atmospheric pressure of 14.7 psia, if you will be at a saturated liquid and when more heat is added, it is latent head changing it to a gas. If however you are at a closed container where the can physically alter the "atmospheric pressure" in the container to 10 psia, the vapor pressure and the "atmospheric pressure" of 10 psia will be equal at a lower temperature and the liquid will boil. In a refrigeration cycle however, I am confused about where the "atmospheric pressure" comes into play. After a compressor compresses a superheated vapor gas, because the molecules move faster in a smaller volume, you get a higher pressure/temperature gas. This rule applies anywhere. What I don't get is when it turns into a liquid in the condensor. If you remove 'x' amount of heat from the superheated vapor once it leaves the compressor, you will reach a point where it will condense into a liquid. In the closed container above at 10 psia "atmospheric pressure", I would know at what temperature that once I reach and remove further heat, condensation will occur because the VP of the evaporated water and the 10 psia would match. In the condensor though, what is the "atmospheric pressure" here? Where does it comes from and how would I change it? The above can also be applied to the evaporator, low-pressure side. Is it the size of the tubing that controls the "atmospheric pressure" here in both the evaporator and condensor coils or something else?