If the propane level remains constant but the ambient temperature drops, what happens to vaporization rate/pressure?

When the ambient temperature drops, the vaporization rate and pressure of propane decrease. This is primarily due to the properties of propane and the principles of gas behavior. Propane, like all liquids, requires heat to convert from a liquid to a vapor. At lower temperatures, the kinetic energy of the propane molecules is reduced, leading to fewer molecules escaping from the liquid phase into the vapor phase.

As a result, the pressure in the vapor space above the liquid propane also decreases because there are fewer molecules in the vapor phase. This phenomenon aligns with the general gas laws and thermodynamics—higher temperatures support higher vaporization rates and pressures. Thus, maintaining a constant liquid level in the storage does not overcome the impact of cooler temperatures, which inherently restrict the vaporization process.