VII. ATMOSPHERIC STABILITY

Review Questions

1. a) What is an adiabatic process? b)Why is there a decrease in temperature of the air parcel as it rises adiabatically? c) Why does air that is warmer that its surroundings rise? d) Why does cold air sink? 2. a)What are the three different lapse rates types called? b) When will an air parcel change from cooling at the Dry Adiabatic Lapse Rate (DALR) to the Wet or Saturated Adiabatic Lapse Rate (SALR)? 3. a)Why is the SALR not constant? b)What is the name of the energy that is released? c) If two air parcels are cooling at -6 deg C / km or -9 deg C/ km respectively, which has the most moisture present? 4. a) Draw a graph which shows what the temperature of an air parcel will be at 1000 m (z=1000 m) if the air temperature at the surface (z=0 m) is 12 deg C. Show by calculation that you can obtain the same answer. b) If the condensation level is at 500 m and the SALR is -7.5deg C /km, what would the air temperature be at 1000 m? c) Where is the bottom (base) of the clouds? d)What is the dew point temperature at this level? 5. a) What is atmospheric stability a measure of? b) If air has a tendency to rise what type of stability conditions are these? 6. Stable air conditions occur when the air parcel is cooler than its surroundings whether the air parcel is dry or saturated. Draw a graph to show stable conditions with the Environmental Lapse Rate (ELR), DALR and SALR shown. 7. If the air is conditionally unstable (there is conditional instability) what is the relation between the three lapse rates? 8. a)What is the difference between lapse and inversion conditions? b) Under which conditions is air pollution likely to be more significant? c)Why are air pollutants dispersed under unstable conditions and not under stable conditions? 9. a) Draw a graph which has the ELR given in the table below. b) If an air parcel was dry and tried to rise adiabatically what would the stability be? Would it rise? c) If the parcel was saturated (SALR = -6 deg C/ km) would this change the ability of the air to rise? Temperature ( deg C) 20 15 Height (m) 0  1000 10. Why does intense solar heating increase instability? 11. a) If an air mass moves from a cold surface over a warmer surface what would the influence be on stability? Why? b) Give an example of where and when this occurs. 12. Forceful uplift occurs in a number of different ways. Draw diagrams to show the following cases: a) orographic uplift b) convergence c) frontal wedging. d) Give examples of locations in the US where each is likely to occur.