Atmospheric Thermal Structure

Question 1

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

Answer 1

Troposphere

Question 2

What determines how a pollutant can disperse through the atmosphere?

Answer 2

Rate of change of temperature with altitude.

Question 3

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

Answer 3

Pressure, Density, and temperature.

Question 4

How is the atmosphere divided into layers?

Answer 4

By the vertical distribution of temperature.

Question 5

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

Answer 5

True

Question 6

Lapse Rate

Answer 6

Γ = -dT/dz

Question 7

What are the features of the boundary layer?

Answer 7

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

Question 8

What does the boundary layer depend on?

Answer 8

Ground temperature

Question 9

How is a surface inversion created during the night?

Answer 9

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

Question 10

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

Answer 10

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

Question 11

Ideal gas law specifically for dry air?

Answer 11

p = ρd Rd T

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

Question 12

Ideal gas law for moist air?

Answer 12

p = ρv Rd Tv

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

Question 13

What is virtual temperature tv?

Answer 13

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.

Question 14

What is the virtual temperature formula?

Answer 14

Tv = [1 + 0.61*rv ] * T

Question 15

Hydrostatic Equations

Answer 15

F pressure = F gravity
−δp = gρδz

At the limit of δz -> 0
∂p/ ∂z = -g*ρ

Question 16

Hydrostatic balance with ideal gas law:

Answer 16

∂p/ ∂z = - p*g/ Rd * Tv

Question 17

1st law of thermodynamics

Answer 17

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.

Question 18

Isobaric

Answer 18

Constant pressure
dp = 0
δq = cp*dT

Question 19

Isothermal

Answer 19

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

Question 20

Isochoric

Answer 20

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

Question 21

Adiabatic

Answer 21

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

Question 22

How does temperature change with height for a rising thermal?

Answer 22

Temperature is the highest when nearer to the ground

Question 23

Dry adiabatic lapse rate

Answer 23

-dT/dz = cp/g = Γd

Question 24

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

Answer 24

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

Question 25

Saturated Adiabatic lapse rate

Answer 25

Γs - not a constant like dry adiabatic lapse rate Γs - depends on net amount of condensation -dT/dz = Γs = Γd [1 + (Lv+Ws/Rd*T)/ 1+ (Lv^2*ws/Rv*cp*T^2)] Answer in bracket is always smaller than 1, so Γs < Γd

Question 25

Saturated Adiabatic lapse rate

Answer 25

Γs - not a constant like dry adiabatic lapse rate Γs - depends on net amount of condensation -dT/dz = Γs = Γd [1 + (Lv+Ws/Rd*T)/ 1+ (Lv^2*ws/Rv*cp*T^2)] Answer in bracket is always smaller than 1, so Γs < Γd

Question 26

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

Answer 26

True

Question 27

Potential Temperature

Answer 27

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

Question 28

What process is potential temperature?

Answer 28

A conserved adiabatic processes

Question 29

What are the four concepts of stability?

Answer 29

Stable Neutral Unstable Conditionally unstable

Question 30

Stable

Answer 30

Returns to its original position after displacement

Question 31

Neutral

Answer 31

Remains in new position after being displaced

Question 32

Unstable

Answer 32

Moves further away from its original position after being displaced

Question 33

Conditionally unstable

Answer 33

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

Question 34

Buoyancy

Answer 34

Ftot = (ρ env + ρ parc)* V*g

Question 35

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 . . .

Answer 35

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

Question 36

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

Answer 36

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

Question 37

Buoyancy force in terms of T

Answer 37

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

Question 38

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

Answer 38

atot = (Tparc - Tenv / Tparc ) *g

Question 39

Buoyant

Answer 39

T of parcel > T of environment

Question 40

Sink

Answer 40

T of parcel < T of environment

Question 41

Stays put

Answer 41

T of parcel = T of environment

Question 42

What are the three possibilities for saturated air?

Answer 42

Stable Neutral Unstable

Question 43

Characteristics of stable saturated air

Answer 43

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

Question 44

Characteristics of neutral saturated air

Answer 44

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

Question 45

Characteristics of unstable saturated air

Answer 45

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!

Question 46

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

Answer 46

Absolutely unstable Dry neutral Conditionally unstable Moist neutral Absolutely stable

Question 47

Absolutely unstable

Answer 47

Γenv > Γd > Γs Unsaturated parcel becomes warmer than nearby environment Saturated parcel becomes warmer than nearby environment

Question 48

Dry neutral

Answer 48

Γenv = Γd > Γs Unsaturated parcel becomes equivalent to the nearby environment Saturated parcel becomes warmer than nearby environment

Question 49

Conditionally unstable

Answer 49

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!

Question 50

Moist neutral

Answer 50

Γd > Γenv = Γs Unsaturated parcel becomes colder than nearby environment Saturated parcel becomes equivalent to the nearby environment

Question 51

Absolutely stable

Answer 51

Γd > Γs > Γenv Unsaturated parcel becomes colder than nearby environment Saturated parcel becomes colder than nearby environment

Question 52

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

Answer 52

fanning

Question 53

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

Answer 53

Looping

Question 54

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

Answer 54

Coning

Question 55

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

Answer 55

Lofting

Question 56

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

Answer 56

Funmigation