This brings us to trying to understand what it means to have a stable or unstable air mass situation. An absolutely stable atmosphere is when the environmental lapse rate, or the actual lapse rate is less than the moist adiabatic lapse rate. The air parcel that is rising is cooling faster than the environment even during saturation. The air mass is prevented from continually rising. An absolutely unstable atmosphere is when the environmental lapse rate or the rate of temperature reduction with elevation is greater than the dry adiabatic lapse rate. The air may be saturated or unsaturated but it cools at a slower rate than the environment, so always be warmer and will always continue to rise. Finally, there is the conditionally unstable environment, where the environmental lapse rate is somewhere between the wet and dry adiabatic lapse rates. Exactly what happens depends on how saturated the air is with moisture. If the moisture levels are high, it will cool closer to the rate we see in the wet adiabatic lapse rate, and you will get continual rise of the air parcel. You can often plot the rate at which an air parcel cools with elevation, noting that at some point the air parcel will become completely saturated. What happens then? This is when and where clouds form. The term Lifting Condensation Level or LCL is this level at which a dry adiabatically lifted air parcel is saturated. You can follow the temperatures as the altitude rises in the air parcel to where it becomes warmer than its environment while it is rising along the moist adiabatic lapse rate line. At the appointed time it becomes warmer than its environment, you would call this the Level of Free Convection or LFC. Further above this, the air parcel will suddenly become cooler than its environment. This is called the equilibrium level or EL.
CLOUDS AND CONVECTION Now that you have some idea of how air moves, rises, and falls, you should be able to better understand exactly how clouds form in more detail. Clouds as you know are collections of suspended water or ice particles somewhere in the atmosphere. While these suspended particles do have weight and do fall from the sky, while in a cloud their mass is so small they are in effect suspended.
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