Radiation balance

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Radiation balance of the Earth surface

Radiation balance of the Earth surface

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Radiation balance of the surface influences: Temperature regime in the soil

Radiation balance of the surface influences:

Temperature regime in the soil

and the surface layer of the atmosphere.
Processes of fog and frost formation.
Air mass transformation.

Radiation balance varies depending on latitude, time of the year and day, and weather conditions.

Radiation balance can be calculated for various time intervals: minutes, hours, days, weeks etc.
It can be positive ( income exceeds outlay) and negative (the body emits more energy than absorbs)

Radiation balance is subject for annual and diurnal variations.

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Annual and diurnal variations of the radiation balance of the Earth

Annual and diurnal variations of the radiation balance of the Earth

surface.

April

June

October

An important feature of the radiation balance is its transfer via 0. Usually, it happens at the time when Sun altitude reaches 10 -15°. In case of snow cover existence it occurs at the Sun altitude 20 - 25°. This means that the time interval with positive radiation balance becomes much shorter.

For a location at 60°N latitude

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Some particularities of the radiation balance annual variation Annual variation of

Some particularities of the radiation balance annual variation

Annual variation of the

radiation balance depends on latitude and type of underlying surface.
Tropical area: radiation balance is always positive.
Antarctic area: radiation balance is always negative due to large value of the surface albedo.
At 60° latitude: radiation balance is positive 6 – 8 months a year.
In arctic area there are some places where radiation balance (average for a year) is positive. It is valid for the places with snow and ice free surfaces for at least 2 months. The Sun shines here 24 hours at summer months.
Question: Where radiation balance is larger on ocean or on land at the same altitude and weather conditions?
Answer: On ocean, since water surface albedo is less than that of land
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Radiation balance depends on Sun altitude, albedo and cloudiness. Parameters “a”

Radiation balance depends on Sun altitude, albedo and cloudiness.

Parameters “a” and

“b” depends on albedo of the underlying surface.

Cloudiness impact

When R>0, cloudiness causes the net and effective radiation decrease. But the net radiation decrease is much stronger. Therefore, the radiation balance decreases at cloudiness condition.
When R<0, cloudiness causes the effective radiation decease and, hence, decrease of radiation balance absolute value.
Conclusion: cloudiness always decreases the radiation balance absolute value

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Radiation balance of the atmosphere Ua Qa Surface radiation Transmission function

Radiation balance of the atmosphere

Ua

Qa

Surface radiation

Transmission function

Part of the surface radiation

that goes into the space
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Calculations done with this formula have shown that the RA values are negative over whole globe.

Calculations done with this formula have shown that the RA values

are negative over whole globe.
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Radiation balance of the Earth as a whole planet We’ll discuss

Radiation balance of the Earth as a whole planet

We’ll discuss the

balance of radiative energy in a vertical column including active layer of soil ( water) and the atmosphere.

Outgoing part

Incoming part

Every unit of time the Earth receives the amount of SR equal to the product of the solar constant by the area of the Earth cross section i. e.

Due to Earth rotation this energy is distributed over the all surface of the globe that is

Near equator RE>0 over the whole year. In the middle latitudes RE>0 is observed only in summer.