Plot the following environmental sounding, consisting of six (T,z) pairs: (15,0)
ID: 108542 • Letter: P
Question
Plot the following environmental sounding, consisting of six (T,z) pairs: (15,0), (13,100), (10,400), (10,600), (12,1000), (10,1300), where temperatures are in degrees celcius and heights are in meters.
Even though z is the independent variable, plot z on the ordinate rather than the abscissa in conformance with normal meteorological practice. The 6 points in this sounding define 5 layers in which lapse rates are constant, but differ from layer to layer. Label the layers A through E, where A is the lowest layer and E is the highest layer.
Draw a dashed line somewhere on the plot indicating the slope of the dry adiabatic lapse rate. Label the dashed line as 'gamma sub d=9.8°C/km ~ 10°C/km.' Remember that the lapse rate is defined as the rate of DECREASE of temperature with height. A lapse rate is positive if temperature decreases with height, and negative if temperature increases with height.
1. Assume that the air in the sounding is unsaturated, and answer the following questions:
a. What is the lapse rate in each of the layers A-E?
A _____ °C/km
B _____ °C/km
C _____ °C/km
D _____ °C/km
E _____ °C/km
b. What is the stability of each of the layers (stable, neutral, or unstable)?
A _____
B _____
C _____
D _____
E _____
Now, suppose that the moist adiabatic lapse rate is 5°C/km. Remember that the moist adiabatic lapse rate, while variable, must always be less than or equal to the dry adiabatic lapse rate. Draw a dot-dash line somewhere on the plot indicating the slope of the moist adiabat. Label it 'gamma sub m=5°C/km.'
2. Assume that the air in our environmental sounding is saturated, and answer the following question:
a. What is the stability of each of the layers (stable, neutral, or unstable)?
A _____
B _____
C _____
D _____
E _____
3. Assume that you do not know if the air in the environmental sounding is saturated or unsaturated, and answer the following question:
a. Which of the layers in the sounding is conditionally unstable?
Now, without regard to the graph, answer the two following questions:
4. An unsaturated parcel, if taken from any height in an environmental sounding, will cool at what rate when lifted?
_____ °C/km
5.. An unsaturated parcel, if taken from any height in an environmental sounding, will warm at what rate when it sinks?
_____ °C/km
6. Suppose we have a cloudy parcel at a temperature of 10°C at 1km height. The parcel sinks to cloud base at 800 m height and then continues to sink to sea level. What will its temperature be at sea level?
_____ °C/km
7. What is the typical tropospheric lapse rate, as given in the Standard Atmosphere?
_____ °C/km
8. Compare the standard atmosphere's typical value of lapse rate with the dry adiabatic lapse rate. Would you say that the atmosphere is typically stable or unstable?
Explanation / Answer
1. a. Since the air is unsaturated therefore lapse rate will vary according to the dry adiabatic lapse rate which is 10 degree celsius reduce in temperature per km rise in elevation.
Lapse rate in layers A-E will be
A=10 degree celsius/km
B=10 degree celsius/km
C=10 degree celsius/km
D=10 degree celsius/km
E=10 degree celsius/km
b. E- The first layer A is since the temperature of the first layer is equal to the dry adiabatic lapse rate. Here the first layer is at heights of 100 m. Similarly dry adiabatic lapse rate for 100 m rise in elevation will be 1 degree reduce in temperature i.e 14 degree celsius. But here for the first layer the temperature of the prevailing air at 100 m is 13 degree celsius which means that the prevailing lapse rate is less than the dry adiabatic lapse rate therefore the air is stable.
B- The temperature of the prevailing lapse rate is10 degree celsius at and elevation of 400m whereas the dry adiabatic lapse rate will be 11 degree celsius. Therefore the prevailing lapse is less than the dry adiabatic lapse rate so the air is stable.
C- The temperature of the air at 600 m elevation is 10 degree whereas for the same elevation the dry adiabatic lapse rate will be 9 degree celsius which means that dry adiabatic lapse rate is greater than the prevailing lapse rate and hence air is unstable.
D- For the D layer, the temperature of the air at 1000 m elevation is 12 degree celsius the temperature is increasing with elevation instead of decreasing which means that inversion is present which gives stability to the air and hence air is stable.
E- Since in the E layer the temperature at a height of about 1300 m is 10 degree celsius whereas the dry adiabatic lapse rate for the same elevation will be 3 degree celsius so the air is unstable.
4. An unsaturated air parcel taken from any height in the sounding will always cool at dry adibatic lapse rate of 10 degree celsius/km when it lifts
5. Similarly, an unsaturated air parcel taken from any height in the sounding will always warm at the dry adiabatic lapse rate of 10 degree celsius/km when sinks.
7. The tropospheric lapse rate is 6.5 degree celsius/km which means that in troposphere there will be a reduction of 6.5 degree celsius in the temperature for every 1000m rise in the elevation of the atmosphere.