Questions on Cloud Formation and Atmospheric Stability
1. Draw the temperature as a function of height inside an air parcel that is rising adiabatically if:
(i) its temperature at the surface is 30 C.
(ii) Cloudbase is at 0.5 km altitude.
(iii) All the cloud drops freeze at 2 km altitude.
2. What is the dewpoint temperature at cloudbase in question 1?
3. Suppose the environmental temperature is 29 C at the surface. How far will the air parcel of question 1 rise (if not forced ) in the following environments?
(i) Environmental temperature decreases at 4 C/km.
(ii) Environmental temperature decreases at 8 C/km.
(iii) Environmental temperature decreases at 10 C/km.
4. What could force an air parcel to rise if it is colder than its environment?
5. What kinds of clouds would form in the environment of question 3(ii) and why?
6. Why do we sometimes see convective clouds forming partway up the mountains or over the lake on hot summer days when the rest of the surroundings are clear?
7. (Demonstration).
(i) The RH inside the jars initially was very slightly below 100%.
(ii) Why was there no cloud in the jars until the pressure was decreased?
(iii) Why did cloud form in only one jar when the pressure was decreased?
(iv) What atmospheric process was simulated by depressurizing the jars?
(v) Why did the cloud disappear when air was added to the jar?