The change in saturation temperature as a zeotropic blend boils or condenses at constant pressure.
A single-component refrigerant boils at one temperature for a given pressure. A zeotropic blend does not: its components boil off at different rates, so the saturation temperature changes across the coil even at constant pressure. That span is the glide.
Glide is why blends have two PT columns (dew point and bubble point) and why they must be charged as liquid. R-407C has significant glide; R-410A has so little that it is treated as a near-azeotrope.
Exam work areas
B · Tools, piping and refrigerant handling E · Commissioning and start-up