Transpiration is the process plants use to move water and nutrients through plant tissue to the surrounding periphery. When air temperature changes, the volume of the air will increase and/or decrease but the water content will remain constant. This will result in a change to the relative humidity but not the actual water content, or absolute humidity. This is important because condensation occurs at an absolute humidity concentration regardless of its relative humidity. This is known as the constant dewpoint temperature, which is a key metric in creating vapor pressure deficits for healthy plant growth.