Heat fluxes in the atmosphere

Сентябрь 3, 2022

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Heat fluxes in the atmosphere

Содержание

2. Climate_Change_Attribution.
3. Heat flux notion The quantity being transferred by the air parcels in a unit of time
4. Convective and advective heat fluxes Any air particle contains some amount of heat. When moving, it
5. Eddy heat flux Eddy heat flux is caused by wind velocity pulsation General conditions for eddy
6. The strongest flux The weakest flux Along with vertical eddy flux there are horizontal fluxes. At
7. Eddy heat exchange differs from that of other substances. Coefficients A and K (for eddy heat
8. Individual and local (partial) derivatives When an air parcel moves, its state parameters are not necessarily
9. Energy equation Temperature variation is of prime interest for meteorologists. It depends on heat influx. It
10. The same reasoning can be applied for horizontal heat fluxes Eddy heat influx Since the horizontal
11. All members of this formula have the same order of magnitude Substituting and into energy equation,
12. After substituting into the basic equation and solution with respect to , we obtain This quantity
13. Air temperature variation due to advection Air temperature variation due to vertical motion Air temperature variation
14. 1. Non-periodical T variations Above boundary layer (in the free atm.) Small time intervals (about 24
15. 2. Periodical T variations Within the boundary layer (diurnal T variations) long time intervals ? only
16. 3. Air mass moving over non-homogeneous surface Advection and eddy exchange are important Taking steady state
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Climate_Change_Attribution.

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Heat flux notion
The quantity being transferred by the air parcels in a

unit of time through a unit of area facing the transfer direction is called HEAT FLUX.
There are convective heat flux and eddy heat flux.
Convective heat flux, in turn, is divided into advective one (horizontal heat transfer) and real convective (vertical heat transfer).
In meteorology, the horizontal heat flux is called advective flux (Qa), and the vertical one is called convective flux (Qc).

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Convective and advective heat fluxes
Any air particle contains some amount of

heat. When moving, it carries this heat along. By this way the heat is distributed in the atmosphere. However, that is not the only way for the heat distribution. Not less effective way is EDDY MIXING (EXCHANGE)

Incoming heat flux is positive, outgoing flux is negative.

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Eddy heat flux
Eddy heat flux is caused by wind velocity pulsation
General

conditions for eddy exchange

Permanency
Conservation
Passivity

Quantity does not satisfy this conditions. Air temperature changes as the air ascending or descending. However, potential temperature satisfy.

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The strongest flux
The weakest flux
Along with vertical eddy flux there are

horizontal fluxes.

At the same level

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Eddy heat exchange differs from that of other substances. Coefficients A

and K (for eddy heat exchange) are called coefficient of eddy heat conductivity and temperature conductivity respectively.

As the stratification is stable ( ) eddy heat flux directed downward

As the stratification is unstable ( ) eddy heat flux directed upward

Heat influx (outflow) notion

Heat influx = incoming heat flux – outgoing heat flux

Heat outflow

Heat influx

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Individual and local (partial) derivatives
When an air parcel moves, its state

parameters are not necessarily constant; they are function of coordinates and time.
For the moving parcel, the coordinates, in turn, are functions of time.

Individual derivative

Local derivative

Convective derivative

Advective derivative

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Energy equation
Temperature variation is of prime interest for meteorologists. It depends

on heat influx. It can be determined on the base of the energy conservation equation.
Heat influx:

Heat influx unit

Mass of the volume is

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The same reasoning can be applied for horizontal heat fluxes
Eddy heat

influx

Since the horizontal exchange is much smaller the vertical one, for practical purposes this formula can be simplified

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All members of this formula have the same order of magnitude
Substituting
and
into

energy equation, we obtain

See the next slide

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After substituting into the basic equation
and solution with respect to

, we obtain

This quantity is small and can be neglected

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Air temperature variation due to advection
Air temperature variation due to vertical

motion

Air temperature variation due to eddy mixing

Air temperature variation due to radiation and water phase transfer

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1. Non-periodical T variations
Above boundary layer (in the free atm.)
Small time

intervals (about 24 h)
? no heat influx ? adiab. process
Energy equation:

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2. Periodical T variations
Within the boundary layer (diurnal T variations)
long time

intervals
? only vertical eddy heat influx
Energy equation ( or equation of the conductivity of the atm.):

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3. Air mass moving over non-homogeneous surface
Advection and eddy exchange are

important
Taking steady state process
The process is called
air mass transformation
Energy equation

Heat fluxes in the atmosphere

Содержание

Climate_Change_Attribution.

Heat flux notionThe quantity being transferred by the air parcels in a

Convective and advective heat fluxesAny air particle contains some amount of

Eddy heat fluxEddy heat flux is caused by wind velocity pulsationGeneral

The strongest fluxThe weakest fluxAlong with vertical eddy flux there are

Eddy heat exchange differs from that of other substances. Coefficients A

Individual and local (partial) derivativesWhen an air parcel moves, its state

Energy equationTemperature variation is of prime interest for meteorologists. It depends

The same reasoning can be applied for horizontal heat fluxesEddy heat

All members of this formula have the same order of magnitudeSubstitutingandinto

After substituting into the basic equation and solution with respect to

Air temperature variation due to advectionAir temperature variation due to vertical

1. Non-periodical T variationsAbove boundary layer (in the free atm.)Small time

2. Periodical T variationsWithin the boundary layer (diurnal T variations)long time

3. Air mass moving over non-homogeneous surfaceAdvection and eddy exchange are

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