Using your profiles on Figure 8.5, complete the following: a) The pressure level at which the parcel first becomes warmer than the environment is referred to as the level of free convection (LFC); if a surface parcel is forced to this height, it will become warmer than its environment and will rise on its own. At what pressure does this occur? b) The region on the thermodynamic diagram where the parcel's temperature is warmer than that of the environment is proportional to a quantity called convective available potential energy, or CAPE. The upward force, or buoyancy of an air parcel, is proportional to the temperature difference between the parcel and its environment. Therefore, the greater the CAPE, the greater the upward force a parcel should experience, resulting in an unstable atmosphere. Lightly shade in the region of CAPE on the diagram. c) The level where the parcel again becomes cooler than the environment provides an estimate for the cloud-top height. In general, the cloud top will be a bit higher than this level due to the upward motion generated in the region of positive CAPE. At what pressure would you expect to see cloud tops? Pressure (mb) 200 300 400 500 600 700 800 900 1000 -60 -------.. -50 -40 -30 -10 0 Temperature (C) -20 20 40 10 20 30 12 10 40 Figure 8.5 Complete thermodynamic diagram, with dry adiabats (solid curved), moist adiabats (dashed curved), and lines of constant mixing ratio (dash-dot). Altitude (km)