Written by Christos I. Vournas,
M.sc. mechanical engineer
We do planets and moons surface temperatures comparison.
The presence of atmosphere doesn't warm Earth's surface.
It is the other reasons, not the presence of atmosphere, that make Earth warmer than the Moon by +68°C.
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Key words:
Specular Reflection
Φ - Solar Irradiation Accepting Factor (spherical shape and surface roughness coefficient), for smooth bodies Φ = 0,47 and for rough / porous Φ = 1
Immediate IR Emission
Rotational Warming Phenomenon ( N*cp )1/16
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The planet blackbody effective temperature formula
Te = [ (1 – a)S /4σ ]¹∕ ⁴
is not capable to provide any realistic planet average temperature approach…
Let’s see why,
Moon’s average distance from the sun
R = 150.000.000 km
or R = 1 AU
(AU is Astronomical Unit, 1AU = 150.000.000 km which is the Earth’s distance from the sun)
In the solar system, for convenience reasons, astronomers use for distances comparison the AU instead of the kilometers.
Moon’s satellite measured average surface temperature (the mean surface temperature)
Tmoon = 220 K
Mars’ distance from the sun
R = 1,524 AU
Tmars = 210 K
Let's continue...
There is the planet blackbody temperature formula, which calculates the planet uniform effective temperature…
It is a theoretical approach to the planet mean surface temperature estimation. It is defined as the temperature planet without atmosphere would have, if planet is considered as a uniformly irradiated blackbody surface.
And therefore it is initially assumed a blackbody planet effective temperature being a uniform surface temperature.
The planet blackbody effective temperature formula:
Te = [ (1 – a)S /4σ ]¹∕ ⁴
a – is the planet average Albedo (dimensionless)
S – is the solar flux on the planet surface W/m²
So – is the solar flux on Earth. (since Earth has atmosphere with clouds, the So is measured above the clouds at the Top of the Atmosphere, or TOA)
So = 1.361 W/m²
S = So*(1/R² )
it is the from the sun distance the square inverse law.
The formula can be written also as
Te = [ (1 – a) So*(1/R² ) /4σ ]¹∕ ⁴
Now, since the formula is a fundamental physics the planet surface average temperature approach, the planets’ effective temperatures should relay accordingly.
So we can write the planet average surface temperature comparison coefficient:
[(1 – a) So*(1/R² ) /4σ ]¹∕ ⁴
Let’s assume comparing the planet’s 1 and the planet’s 2 effective temperatures Te1 and Te2.
Then we shall have:
Te1 /Te2 = [(1 – a1) So*(1/R1² ) /4σ ]¹∕ ⁴ / [(1 – a2) So*(1/R2² ) /4σ ]¹∕ ⁴
(Te1 /Te2 )⁴ = [(1 – a1) /(1 – a2) ]* [(1/R1² ) /(1/R2² )]
Let’s compare Moon’s and Mars’ satellite measured temperatures
Tmoon = 220 K
Tmars = 210 K
(Tmoon /Tmars)⁴ = (220 /210)⁴ = 1,0476⁴ = 1,2045
Let’s compare Moon’s and Mars’ comparison coefficients
[ (1 – a.moon) /(1 – a.mars) ]* [(1/Rmoon² ) / (1/Rmars² ) ]
[ (1 – 0,11) /(1 – 0,25) ]* [(1/1² ) /(1/1,524² ) ]
( 0,89 /0,75)* (1,524² ) = (0,89 /0,75) * 2,32 = 2,75
Conclusion: We obtained on the left side of the comparison equation the
1,2045 number
(for satellite measured planet average surface temperatures comparison) and on the right side the
2,75 number
(for planets’ coefficients comparison)
Consequently we may conclude here, that the planet blackbody effective temperature formula is not capable to provide any realistic planet average temperature approach…
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Te - planet effective temperature
Te = [ (1-a) S /4σ ]¹∕ ⁴
Te.correct - the planet corrected effective temperature
Te.correct = [ Φ (1-a) S /4σ ]¹∕ ⁴
Φ - is the solar irradiation accepting factor (it is the planet surface spherical shape, and planet surface roughness coefficient)
Φ = 0,47 - for smooth surface planets without atmosphere
Φ = 1 - for heavy cratered without atmosphere planets
Φ = 1 - for gases planets
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Te.correct = [ Φ (1-a) S /4σ ]¹∕ ⁴
Tmean = [ Φ (1-a) So (β*N*cp)¹∕ ⁴ /4σ ]¹∕ ⁴
Or
Tmean = Te.correct * [ (β*N*cp)¹∕ ⁴ ]¹∕ ⁴
Table 1. Comparison of Predicted (Tmean) vs. Measured (Tsat) Temperature for All Rock-type Planets
......................Φ..Te.correct ..[(β*N*cp)¹∕ ⁴]¹∕ ⁴..Tmean ...Tsat
................................°K ......................................°K ........°K
Mercury .....0,47....364,0 ........0,8953............. 325,83 ...340
Earth ..........0,47....211 ...........1,368................287,74 ....288.
Moon ..........0,47....224 ...........0.9978.............223,35 .....220
Mars ...........0,47....174 ...........1,227..............213,11 .....210
Io ..................1.......95,16 ........1,169..............111,55 .....110
Europa ........0,47....78,83 ........1,2636.............99,56 .....102
Ganymede...0,47....88,59 ........1,209.............107,14 ....110
Calisto ..........1.....114,66 ........1,1471...........131,52 ....134 ±11
Enceladus .... 1 ......55,97 ........1,3411............75,06 .......75
Tethys ..........1.......66,55 .........1,3145 ...........87,48 .......86 ± 1
Titan .............1.......84,52 .........1,1015 ...........96,03 .......93,7
Pluto .............1.......37 ..............1,1164 ...........41,6 .........44
Charon .........1......41,90 ...........1,2181 ...........51,04 .......53
Conclusion: We can calculate planet mean surface temperature obtaining very close to the satellite measured results.
Tmean = Te.correct * [ (β*N*cp)¹∕ ⁴ ]¹∕ ⁴
where
[ (β*N*cp)¹∕ ⁴ ]¹∕ ⁴ - is the planet surface warming factor
Warming Factor = (β*N*cp)¹∕₁₆
from the incomplete effective temperature equation
Te = [ (1-a) S / 4 σ ]¹∕ ⁴
which is in common use right now, but actually it is an incomplete planet's Te equation and that is why it gives us very confusing results.
to the Planet's Without-Atmosphere Mean Surface Temperature Equation
Tmean = [ Φ (1-a) S (β*N*cp)¹∕ ⁴ /4σ ]¹∕ ⁴ (1)
The Planet's Without-Atmosphere Mean Surface Temperature Equation is also based on the radiative equilibrium and on the Stefan-Boltzmann Law.
The Equation is being completed by adding to the incomplete Te equation the new parameters Φ, N, cp and the constant β.
Φ - is the dimensionless Solar Irradiation accepting factor
N - rotations /day, is the planet’s axial spin
cp – is the planet's surface specific heat
β = 150 days*gr*oC/rotation*cal – is the Rotating Planet Surface Solar Irradiation INTERACTING-Emitting Universal Law constant.
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Table of contents - Links
0). Explain Rotational Warming Model.
Demonstrate the Initial PREMISE, Links: (1) and (2)
3).The Planetary Temperatures Comparison Criteria.
4). "The total amount of the specularly reflected portion of solar flux"
5). How A Planet Retains The Solar Energy - the role of the Immediate IR emission.
6). Φ -Factor is an analogue of the well known Drag Coefficient Cd=0,47
7). “What ‘portion’ of ‘sunlight’ reaches surface of Earth?”
8). The satellites do not measure Bond Albedo.
9). Stefan-Boltzmann formula J = σ T4 W/m² doesn't apply to terrestrial temperatures.
10). The Theoretical Equation.
12). The actual reason of the observed Global Warming.
13). The Axial Precession's role in Global Warming.
14). The Original Milankovitch cycle.
15). The Reversed Milankovitch cycle.
16). The higher CO2 content in ice core samples relates to colder periods.
17). Sensible Heat /Latent Heat ratio.
18). The conventional greenhouses, and the role of immediate IR emission.
19). NASA Technical Memorandum An Earth Albedo Model
20). The yearly total Immediate IR Emitted solar energy - in our times - is lower.
21). The yearly total reflected solar energy - in our times - is lower.
Appendix - Links
1). Earth's Corrected Effective Temperature (210 K ) calculation.
2). Earth's Average Surface Temperature (288 K ) calculation.
3). Moon's Corrected Effective Temperature (224 K ) calculation.
4). Moon's Average Surface Temperature (220 K ) calculation.
5). Mars' Corrected Effective Temperature (174 K ) calculation.
6). Mars' Average Surface Temperature (210 K ) calculation.
7). Mercury's Corrected Effective Temperature (364 K ) calculation.
8). Mercury's Average Surface Temperature (340 K ) calculation.
9). Titan's Average Surface Temperature (93,7 K ) calculation.
10). Earth / Mars satellite measured mean surface temperatures 288 K and 210 K comparison.
11). Earth's /Moon's temps 288K /220K comparison.
13). Blog.
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The table of contents will be completed some time soon. For more pages view the menu at the top.
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