Absolute Stability

  • consider the diagram to the right, notice that:
  • Tup < Tsp < Te
    • where Tup is the temperature of an unsaturated parcel = 0C
    • Tsp = temperature of a saturated parcel = 10C
    • Te = environmental temperature = 20C.
  • generally, notice that Te is always larger than Tsp and Tup at any level
  • Hence, an unsaturated or saturated parcel will always be cooler than the environment and will sink back down to the ground
  • This is an example of absolute stability
  • The condition for absolute stability is:
    • Gd>Gm>Ge
  • Gd is the dry adiabatic lapse rate (10C km-1)
  • Gm is the moist adiabatic lapse rate (6C km-1)
  • Ge is the environmental lapse rate (variable - 0C km-1 in this case)

Q: How would you characterize the stability of an inversion layer?