Question

Environmental Lapse Rate and Parcel Worksheet Instructions: For parts A, B, and C, an entry is required at each "?". For part D, your response should be about 2-3 sentences. A. Using the lapse rates provided complete all items. Environment temp (deg C) Parcel temp (deg C) dew point (deg ) height (km) -9 dew point (deg C) -15 -5 5 14 21 20 ? ? ? ? 28 ? ? ? ? 20 0 28 B. What is the condensation level (if any)? level (km) temp (deg C) C. Where does the parcel temperature exceed the environmental temperature (if any)? level (km) temp (deg C) ?

The adiabatic process uses specific numbers, or rates, to decrease a parcel’s temperature and dew point temperature. Those rates are:

- Unsaturated air will decrease by 10 deg C for every 1 kilometer (km) of lift. This is called the dry adiabatic lapse rate.

- Saturated air will decrease by 6 deg C for every km of lift. This is called the moist adiabatic lapse rate.

- The parcel’s dew point temperature will decrease by 2 deg C for every km of lift in unsaturated air and will decrease at the moist adiabatic rate in saturated air. NOTE: The dew point temperature at a particular level is never greater than the temperature at that level.

The actual change in temperature measured in the atmosphere by a radiosonde is called the environmental lapse rate.

1. Assess, under given conditions, if a lifted parcel of air can reach a level where instability numerically occurs - What are the missing calculations?

Answer 1

A.All the temperatures at different altitudes have been shown on the attached table.

B.Comparing the temperatures of the parcel and the dew point temperatures at corresponding altitudes, we see that the parcel reaches the dew point temperature at 1 km height. At this level, the air parcel is saturated with the water vapour present within itself. This is the level of condensation of the parcel. At this level, the parcel will start to condense some of the water vapour present in it.
So, the level of condensation=1 km altitude
Temperature at this point=18°C
C.At an altitude of 5 km, the temperature of the air parcel is greater than the environmental temperature. At this altitude, environmental temperature is -9°C and the temperature of the air parcel is -6°C.
When the temperature of the air parcel is less than the environmental temperature, the air parcel is stable at those conditions. Warmer air is lighter than colder air mass and tries to remain atop of the colder air mass. When the temperature of the air parcel is less than the temperature of the environment at the same height, the air parcel is heavier than the surrounding air and the tendency of the parcel of air is to move downward. When this situation inverses, the air parcel tries to rise through the surrounding environment. This state is known to be unstable. In the present case, thi happens at an altitude of 5 km in the atmosphere.
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Parcel
Height	Temp	Dew point
0	28	20
1	18	18
2	12	12
3	6	6
4	0	0
5	-6	-6