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ENVE 130 > Atmospheric Thermal Structure > Flashcards

Atmospheric Thermal Structure Flashcards

1
Q

What layer of the atmosphere contains 80% of the total mass of the atmosphere and almost the whole quantity of water vapor?

A

Troposphere

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2
Q

What determines how a pollutant can disperse through the atmosphere?

A

Rate of change of temperature with altitude.

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3
Q

What are the physical properties of the atmosphere (state variables)?

A

Pressure, Density, and temperature.

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4
Q

How is the atmosphere divided into layers?

A

By the vertical distribution of temperature.

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5
Q

T/F: In the troposphere, temperature decreases with height?

A

True

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6
Q

Lapse Rate

A

Γ = -dT/dz

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7
Q

What are the features of the boundary layer?

A
  1. Surface Layer
  2. Convective mixed layer
  3. Temperature Inversion Layer
  4. Residual Layer
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8
Q

What does the boundary layer depend on?

A

Ground temperature

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9
Q

How is a surface inversion created during the night?

A

The ground cools radiatively, causing air temperatures to increase with increasing height from the ground.

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10
Q

T/F: Pollutants are more likely to be trapped in the surface layer at day?

A

False, because the surface inversion causes pollutants to stay trapped.

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11
Q

Ideal gas law specifically for dry air?

A

p = ρd Rd T

  • ρ is rho, density
    Rd = R*/ Md, gas constant
    T = temperature
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12
Q

Ideal gas law for moist air?

A

p = ρv Rd Tv

  • ρ is rho, density
    Rv = R*/Mw
    Tv = virtual temperature
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13
Q

What is virtual temperature tv?

A

The temperature a
hypothetical sample of dry air would need to have in order to have the same density as the sample of moist air at the same pressure.

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14
Q

What is the virtual temperature formula?

A

Tv = [1 + 0.61*rv ] * T

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15
Q

Hydrostatic Equations

A

F pressure = F gravity
−δp = gρδz

At the limit of δz -> 0
∂p/ ∂z = -g*ρ

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16
Q

Hydrostatic balance with ideal gas law:

A

∂p/ ∂z = - p*g/ Rd * Tv

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17
Q

1st law of thermodynamics

A

With Specific heat capacity

dq = cvdT +pdα

dq = cpdT − αdp

cp = cv + R

Where is cv = 717 JK-1kg-1 and cp = 717 J K-1kg*-1 are the
specific heat at constant volume and pressure respectively.

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18
Q

Isobaric

A

Constant pressure
dp = 0
δq = cp*dT

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19
Q

Isothermal

A

Constant temperature
dT = 0
du = 0 since dT = 0
-> δq = δw
All heat goes into work.

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20
Q

Isochoric

A

Constant volume
dV = 0
δw = 0 since dV = 0 (and dα = 0)
δq = du = cv*dT
No work, all heat into T changes.

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21
Q

Adiabatic

A

No heat exchanged,
δq = 0, du = - δw since δq = 0

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22
Q

How does temperature change with height for a rising thermal?

A

Temperature is the highest when nearer to the ground

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23
Q

Dry adiabatic lapse rate

A

-dT/dz = cp/g = Γd

24
Q

What are the conditions for saturated adiabatic (moist adiabatic)?

A

All condensed water remains in rising air parcel.
No precipitation
Adiabatic - no heat exchanged with environment

25
Q

Saturated Adiabatic lapse rate

A

Γs - not a constant like dry adiabatic lapse rate
Γs - depends on net amount of condensation

-dT/dz = Γs = Γd [1 + (Lv+Ws/RdT)/ 1+ (Lv^2ws/RvcpT^2)]
Answer in bracket is always smaller than 1, so Γs < Γd

25
Q

Saturated Adiabatic lapse rate

A

Γs - not a constant like dry adiabatic lapse rate
Γs - depends on net amount of condensation

-dT/dz = Γs = Γd [1 + (Lv+Ws/RdT)/ 1+ (Lv^2ws/RvcpT^2)]
Answer in bracket is always smaller than 1, so Γs < Γd

26
Q

T/F: Saturated lapse rate - Γs- decreases with increasing moisture content (and thus temperature)

A

True

27
Q

Potential Temperature

A

θ - as
the temperature a parcel would have if it
adiabatically moved from existing pressure to a
standard pressure, defined as p0 ≡ 1000 hPa.

28
Q

What process is potential temperature?

A

A conserved adiabatic processes

29
Q

What are the four concepts of stability?

A

Stable
Neutral
Unstable
Conditionally unstable

30
Q

Stable

A

Returns to its original position after displacement

31
Q

Neutral

A

Remains in new position after being displaced

32
Q

Unstable

A

Moves further away from its original position
after being displaced

33
Q

Conditionally unstable

A

Becomes unstable for a large enough vertical displacement
- This is the most common instability in the atmosphere

34
Q

Buoyancy

A

Ftot = (ρ env + ρ parc)* V*g

35
Q

If density of air parcel (ρparc) is
greater than the density of
environmental air (ρenv) that it
displaces, then the air parcel will
experience a . . .

A

downward directed total (buoyancy + gravity) force (Ftot):
ρ parc > ρ env

36
Q

If density of air parcel (ρparc) is less
than density of the environmental
air (ρenv) that it displaces, then air
parcel will experience an . . .

A

upward directed total (buoyancy + gravity) force (Ftot)
ρ parc < ρ env

37
Q

Buoyancy force in terms of T

A

Parcel’s density immediately adjusts to environment (like a balloon!)
- Differences in density are due to differences in T

38
Q

(Ftot = (ρ env + ρ parc)* V*g) + (ρ = p/ Rd Tv)

A

atot = (Tparc - Tenv / Tparc ) *g

39
Q

Buoyant

A

T of parcel > T of environment

40
Q

Sink

A

T of parcel < T of environment

41
Q

Stays put

A

T of parcel = T of environment

42
Q

What are the three possibilities for saturated air?

A

Stable
Neutral
Unstable

43
Q

Characteristics of stable saturated air

A

Γenv < Γd –> dθ/ dz > 0
-Parcel becomes
colder than nearby
environment
-Downward buoyancy force
- Parcel will return to original location

44
Q

Characteristics of neutral saturated air

A

Γenv = Γd –> dθ/ dz = 0
-Parcel T becomes equal to
environment
-No buoyancy force
- Parcel will remain at new location

45
Q

Characteristics of unstable saturated air

A

Γenv > Γd –> dθ/ dz < 0
-Parcel becomes
warmer than environment
-Upward buoyancy force
- Parcel will move further away from original location

Unsaturated air is unstable if θ decreases with z!

46
Q

What are the 5 possibilities for moist air (either saturated or unsaturated)?

A

Absolutely unstable
Dry neutral
Conditionally unstable
Moist neutral
Absolutely stable

47
Q

Absolutely unstable

A

Γenv > Γd > Γs

Unsaturated parcel becomes warmer than nearby environment

Saturated parcel becomes warmer than nearby environment

48
Q

Dry neutral

A

Γenv = Γd > Γs

Unsaturated parcel becomes equivalent to the nearby environment

Saturated parcel becomes warmer than nearby environment

49
Q

Conditionally unstable

A

Γd > Γenv > Γs

Unsaturated parcel becomes colder than nearby environment

Saturated parcel becomes warmer than nearby environment

*The vertical temperature profile at many locations in our atmosphere is conditionally
unstable!

50
Q

Moist neutral

A

Γd > Γenv = Γs

Unsaturated parcel becomes colder than nearby environment

Saturated parcel becomes equivalent to the nearby environment

51
Q

Absolutely stable

A

Γd > Γs > Γenv

Unsaturated parcel becomes colder than nearby environment

Saturated parcel becomes colder than nearby environment

52
Q

At stable atmosphere, what is the application of the source?

A

fanning

53
Q

At unstable atmosphere, what is the application of the source?

A

Looping

54
Q

At neutrally stable, what is the application of the source?

A

Coning

55
Q

At smokestack above the inversion layer, what is the application of the source?

A

Lofting

56
Q

At smokestack under the inversion layer, what is the application of the source?

A

Funmigation

ENVE 130 (3 decks)

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