Entropy and Potential Temperature Questions and Answers

Q: Assertion (A): Potential temperature is conserved during dry adiabatic descent. Reason (R): The definition of potential temperature removes the effect of adiabatic compression. Select the correct answer from the options below.

The potential temperature is constructed by undoing the compression, bringing the parcel to a reference pressure, so it cannot be changed by that compression. The reason therefore explains the assertion by construction. The actual temperature rises at the dry adiabatic rate during the descent, which is the change the definition was designed to remove.

Q: Assertion (A): Wet bulb potential temperature identifies an air mass reliably. Reason (R): It is conserved for both dry and saturated adiabatic motion. Select the correct answer from the options below.

Because the quantity survives the ascent and descent an air mass undergoes on its journey, including any condensation and evaporation, it retains the value acquired in the source region. The reason therefore explains the assertion completely. Mixing and diabatic heating do erode the label eventually, which is why air masses gradually lose their identity far from their source.

Q: Statement I: Adiabatic parcels remain on isentropic surfaces. Statement II: Diabatic heating moves a parcel to a higher isentropic surface. In the light of the above statements, choose the correct answer.

Both statements are correct and together they define how isentropic analysis works and where it fails. Adiabatic motion is confined to a surface, so trajectories are two dimensional, and heating moves the parcel across surfaces, which is why trajectories through cloud must be computed diabatically. The two statements bound the applicability of the whole technique.

Q: Consider the following statements about potential temperature. 1. It equals the actual temperature at 1000 hectopascals. 2. It is conserved during dry adiabatic motion. 3. It is conserved during saturated ascent. Which of the statements given above is or are correct?

The first two statements are correct, but latent heat release during saturated ascent raises the potential temperature. Equivalent potential temperature is the quantity conserved in that case. Knowing exactly which processes each conserved variable survives is what allows the right one to be chosen for a given problem.

Q: Consider the following pairs of variable and its reference process. Potential temperature - adiabatic compression to 1000 hectopascals Equivalent potential temperature - condensing all vapour then compressing Wet bulb potential temperature - saturating then descending along a moist adiabat Virtual temperature - adding water vapour at constant pressure How many of the pairs given above are correctly matched?

Virtual temperature is the temperature dry air would need in order to have the same density as the moist sample, which is not a process applied to the parcel but a comparison with a different one. The other three correctly describe the thought experiment defining each quantity. Setting them out as processes rather than as formulae makes their conservation properties much easier to recall. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision.

Q: Which of the following is not conserved for saturated adiabatic ascent? Potential temperature Equivalent potential temperature Wet bulb potential temperature Total water content

Latent heat release raises the potential temperature during saturated ascent, which is precisely why the equivalent and wet bulb forms were introduced. Both of those and the total water content are conserved in the reversible process. In the pseudo-adiabatic idealisation the condensed water is removed, so the total water content is not conserved there either, which is a refinement worth noting.

Q: Two soundings taken a thousand kilometres apart show identical wet bulb potential temperature at 850 hectopascals. What may be concluded?

A conserved air mass label taking the same value at two places indicates that the air has a common origin and has undergone similar processing, which is what defines a single air mass. Surface temperature may differ considerably because of local heating and elevation. A front would appear as a sharp gradient between the two rather than as identical values.

91.

Assertion (A): Potential temperature is conserved during dry adiabatic descent.

Reason (R): The definition of potential temperature removes the effect of adiabatic compression.

Select the correct answer from the options below.

A.A is true but R is false
B.A is false but R is true
C.Both A and R are true, and R is the correct explanation of A
D.Both A and R are true, but R is not the correct explanation of A

Answer: C

The potential temperature is constructed by undoing the compression, bringing the parcel to a reference pressure, so it cannot be changed by that compression. The reason therefore explains the assertion by construction. The actual temperature rises at the dry adiabatic rate during the descent, which is the change the definition was designed to remove.

Discuss in Forum

92.

Assertion (A): Wet bulb potential temperature identifies an air mass reliably.

Reason (R): It is conserved for both dry and saturated adiabatic motion.

Select the correct answer from the options below.

A.Both A and R are true, but R is not the correct explanation of A
B.A is true but R is false
C.A is false but R is true
D.Both A and R are true, and R is the correct explanation of A

Answer: D

Because the quantity survives the ascent and descent an air mass undergoes on its journey, including any condensation and evaporation, it retains the value acquired in the source region. The reason therefore explains the assertion completely. Mixing and diabatic heating do erode the label eventually, which is why air masses gradually lose their identity far from their source.

Discuss in Forum

93.

Statement I: Adiabatic parcels remain on isentropic surfaces.

Statement II: Diabatic heating moves a parcel to a higher isentropic surface.

In the light of the above statements, choose the correct answer.

A.Both Statement I and Statement II are correct
B.Both Statement I and Statement II are incorrect
C.Statement I is correct but Statement II is incorrect
D.Statement I is incorrect but Statement II is correct

Answer: A

Both statements are correct and together they define how isentropic analysis works and where it fails. Adiabatic motion is confined to a surface, so trajectories are two dimensional, and heating moves the parcel across surfaces, which is why trajectories through cloud must be computed diabatically. The two statements bound the applicability of the whole technique.

Discuss in Forum

94.

Consider the following statements about potential temperature.

1. It equals the actual temperature at 1000 hectopascals.

2. It is conserved during dry adiabatic motion.

3. It is conserved during saturated ascent.

Which of the statements given above is or are correct?

A.1, 2 and 3
B.1 and 2 only
C.1 and 3 only
D.2 and 3 only

Answer: B

The first two statements are correct, but latent heat release during saturated ascent raises the potential temperature. Equivalent potential temperature is the quantity conserved in that case. Knowing exactly which processes each conserved variable survives is what allows the right one to be chosen for a given problem.

Discuss in Forum

95.

Consider the following pairs of variable and its reference process.

Potential temperature - adiabatic compression to 1000 hectopascals

Equivalent potential temperature - condensing all vapour then compressing

Wet bulb potential temperature - saturating then descending along a moist adiabat

Virtual temperature - adding water vapour at constant pressure

How many of the pairs given above are correctly matched?

A.Only two
B.All four
C.Only three
D.Only one

Answer: C

Virtual temperature is the temperature dry air would need in order to have the same density as the moist sample, which is not a process applied to the parcel but a comparison with a different one. The other three correctly describe the thought experiment defining each quantity. Setting them out as processes rather than as formulae makes their conservation properties much easier to recall. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision.

Discuss in Forum

96.

Which of the following is not conserved for saturated adiabatic ascent?

Potential temperature

Equivalent potential temperature

Wet bulb potential temperature

Total water content

A.Equivalent potential temperature
B.Wet bulb potential temperature
C.Total water content
D.Potential temperature

Answer: D

Latent heat release raises the potential temperature during saturated ascent, which is precisely why the equivalent and wet bulb forms were introduced. Both of those and the total water content are conserved in the reversible process. In the pseudo-adiabatic idealisation the condensed water is removed, so the total water content is not conserved there either, which is a refinement worth noting.

Discuss in Forum

97.

Two soundings taken a thousand kilometres apart show identical wet bulb potential temperature at 850 hectopascals.

What may be concluded?

A.The two stations lie within the same air mass
B.The two stations have the same surface temperature, since the quantity is derived from that measurement alone
C.Nothing may be concluded
D.A front must lie between them, since air masses of identical properties cannot exist over such a distance

Answer: A

A conserved air mass label taking the same value at two places indicates that the air has a common origin and has undergone similar processing, which is what defines a single air mass. Surface temperature may differ considerably because of local heating and elevation. A front would appear as a sharp gradient between the two rather than as identical values.

Discuss in Forum

98.

The temperature a parcel would have if brought adiabatically to 1000 hectopascals is its _____ temperature.

A.wet bulb temperature, which is reached by evaporating water into the parcel until it becomes fully saturated
B.potential
C.virtual temperature, which is instead the temperature dry air would need to match the density of the sample
D.equivalent

Answer: B

Potential temperature is conserved during dry adiabatic motion and is proportional to the exponential of the specific entropy, which is what makes isentropic and constant potential temperature surfaces identical. Virtual, equivalent and wet bulb temperatures are defined by quite different thought experiments on the same parcel and answer different questions about it. A single measurement chosen to respond to the one asymmetry beats several that respond to shared behaviour.

Discuss in Forum

99.

Arrange the following in increasing order of typical value for a warm moist parcel.

1. Equivalent potential temperature

2. Temperature

3. Potential temperature

4. Virtual temperature

Select the correct sequence.

A.2, 3, 4, 1
B.4, 2, 3, 1
C.2, 4, 3, 1
D.1, 2, 3, 4

Answer: C

For a warm moist parcel near the surface the temperature is lowest, the virtual temperature exceeds it by a few kelvin, the potential temperature exceeds that if the parcel is above 1000 hectopascals, and the equivalent potential temperature is highest of all, giving 2, 4, 3, 1. The ordering is a useful check on any set of computed values.

Discuss in Forum

100.

Match each quantity with what its definition removes or adds.

List I

A. Potential temperature

B. Virtual temperature

C. Equivalent potential temperature

List II

P. adds the latent heat of the vapour

Q. removes the effect of pressure

R. accounts for the density effect of vapour

Select the correct match.

A.A-P, B-Q, C-R
B.A-R, B-P, C-Q
C.A-Q, B-P, C-R
D.A-Q, B-R, C-P

Answer: D

Potential temperature removes the pressure dependence, virtual temperature accounts for the density effect of the water vapour, and equivalent potential temperature adds the latent heat that the vapour would release. Each modifies the plain temperature to answer a specific question, and knowing which question each answers prevents them being confused.

Discuss in Forum

Loading…

Topics

Other Subjects

Tags: Entropy and Potential Temperature Questions and Answers || Entropy and Potential Temperature MCQ Questions and Answers || Entropy and Potential Temperature GK Questions and Answers || Entropy and Potential Temperature GK MCQ Questions || Entropy and Potential Temperature Multiple Choice Questions and Answers || Entropy and Potential Temperature GK || GK on Entropy and Potential Temperature || Atmospheric Thermodynamics Questions and Answers || Atmospheric Thermodynamics MCQ Questions and Answers || Atmospheric Thermodynamics GK Questions and Answers || GK on Atmospheric Thermodynamics

Entropy and Potential Temperature Questions and Answers

Topics

Other Subjects

About Us

Stay informed about all important Dates & Notifications