EXERCISE 1- PROBLEMS/SOLUTIONS-PART I (S.I. Units)
Assume that a parcel of air is forced to rise up and over a 4000-meter-high mountain (shown below). The initial temperature of the parcel at sea level is 30°C, and the lifting condensation level (LCL) of the parcel is 2000 meters. The DAR is 10°C/1000 m and the SAR is 6°C/1000 m. Assume that condensation begins at 100% relative humidity and that no evaporation takes place as the parcel descends.
1. Calculate the temperature of the parcel at the following elevations as it rises up the wind-ward side of the mountain:
(a) 1000 m ______ °C (b) 2000 m ______ °C (c) 4000 m ______ °C
2. (a) After the parcel of air has descended down the lee side of the mountain to sea level, what is the temperature of the parcel? ______ °C
(b) Why is the parcel now warmer than it was at sea level on the windward side (what is the source of the heat energy)?
3. (a) On the windward side of the mountain, is the relative humidity of the parcel increasing or decreasing as it rises from sea level to 2000 meters?
(b) Why?
4. (a) On the lee side of the mountain, is the relative humidity of the parcel increasing or decreasing as it descends from 4000 meters to sea level?
(b) Why?
EXERCISE 2- PROBLEMS/SOLUTIONS-PART II (S.I. Units)
Answer the following questions after completing the problems in Part I. You will also need to refer to the chart of Saturation Mixing Ratios in Table 4-1; interpolate from the chart as needed. As- sume that condensation begins at 100% relative humidity and that no evaporation takes place as the parcel descends.
| Table 4.1 Saturation Mixing Ratio (at Sea-Level Pressure |
| Temperature(oC) |
g/kg |
| -40 |
0.1 |
| -30 |
0.3 |
| -20 |
0.75 |
| -10 |
2 |
| 0 |
3.5 |
| 5 |
5 |
| 10 |
7 |
| 15 |
10 |
| 20 |
14 |
| 25 |
20 |
| 30 |
26.5 |
| 35 |
35 |
| 40 |
47 |
5. (a) On the windward side of the mountain, should the relative humidity of the parcel change as it rises from 2000 m to 4000 m?
(b) Why?
6. As the air rises up the windward side of the mountain:
(a) What is the capacity (saturation mixing ratio) of the rising air at 2000 meters?
(b) What is the capacity of the air at 4000 meters
7. What is the capacity of the air after it has descended back down to sea level on the lee side of the mountain?
8. (a) Assuming that no water vapor is added as the parcel descends down the lee side of the mountain to sea level, is the water vapor content (the mixing ratio) of the parcel higher or lower than before it began to rise over the mountain?
(b) Why?
(c) What is the lifting condensation level of this parcel now?
EXERCISE 2- PROBLEMS/SOLUTIONS-PART III (English Units)
Assume that a parcel of air is forced to rise up and over a 6000-foot-high mountain (shown below). The initial temperature of the parcel at sea level is 76.5°F, and the lifting condensation level (LCL) of the parcel is 3000 feet. The DAR is 5.5°F/1000′ and the SAR is 3.3°F/1000′. Assume that con- densation begins at 100% relative humidity and that no evaporation takes place as the parcel de- scends. Indicate calculated temperatures to one decimal place.
1. Calculate the temperature of the parcel at the following elevations as it rises up the wind-ward side of the mountain:
(a) 1000′________°F (b) 3000′________°F (c) 6000′_________°F
2. (a) After the parcel of air has descended down the lee side of the mountain to sea level, what is the temperature of the parcel?
(b) Why is the parcel now warmer than it was at sea level on the windward side (what is the source of the heat energy)?
3. (a) On the windward side of the mountain, is the relative humidity of the parcel increasing or decreasing as it rises from sea level to 3000 feet?
(b) Why?
4. (a) On the lee side of the mountain, is the relative humidity of the parcel increasing or decreasing as it descends from 6000 feet to sea level?
(b) Why?
EXERCISE 2 PROBLEMS/SOLUTIONS-PART IV (English Units)
Answer the following questions after completing the problems in Part III. You will also need to refer to the chart of Saturation Mixing Ratios in Figure 13-1; interpolate from the chart as needed. Assume that condensation begins at 100% relative humidity and that no evaporation takes place as the parcel descends.
5. (a) On the windward side of the mountain, should the relative humidity of the parcel change as it rises from 3000′ to 6000'?
(b) Why?
6. As the air rises up the windward side of the mountain:
(a) What is the capacity (saturation mixing ratio) of the rising air at 3000 feet?
(b) What is the capacity of the air at 6000 feet?
7. What is the capacity of the air after it has descended back down to sea level on the lee side of the mountain?
8. (a) Assuming that no water vapor is added as the parcel descends down the lee side of the mountain to sea level, is the water vapor
content (the mixing ratio) of the parcel higher or lower than before it began to rise over the mountain?
(b) Why?
(c) What is the lifting condensation level of this parcel now?