Stability in Relation to Cloud Type

1000 = 4,000 feet). This is graphically shown in figure 2-16. This method cannot be applied to all cloud types. It is limited to clouds formed by convection currents, such as summertime cumulus clouds, and only in the locality where the clouds form. It is not valid around maritime or mountainous areas. Stability in Relation to Cloud Type The degree of stability of the atmosphere helps to determine the type of clouds formed. For example, figure 2-17 shows that if stable air is forced to ascend a mountain slope, clouds will be layerlike with little vertical development and little or no turbulence. Unstable air, if forced to ascend the slope, causes considerable vertical development and turbulence in the clouds. The base of this type of cloud can be determined by mechanical lifting as analyzed on a Skew-T. REVIEW QUESTIONS Q2-11. What are the two basic kinds of atmospheric energy? 2-22 MOIST ADIABATIC IN CLOUD DEWPOINT LAPSE RATE DRY ADIABAT 40 50 60 70 80 5,000 4,000 3,000 2,000 1,000 THE AIR DEGREES FAHRENHEIT AG5f0216 Figure 2-16.—Determine of cloud's base when the dew point and temperature are known. AG5f0217 UNSTABLE AIR STABLE AIR Figure 2-17.—Illustration showing that very stable air retains its stability even when it is forced upward, forming a flat cloud. Air which is potentially unstable when forced upward becomes turbulent and forms a towering cloud.