Sentences with phrase «radiative heat transfer only»
Fred Souder says (February 21, 2011 at 3:02 pm):» Again, radiative heat transfer ONLY occurs in the direction from a hot source to a cold source.»
https://wattsupwiththat.com/ Not exact matches
The fact is that Radiative Heat Transfer accounts for only 19 % of the overall transfer of energy from the surface to the atmTransfer accounts for only 19 % of the overall transfer of energy from the surface to the atmtransfer of energy from the surface to the atmosphere.
As you say, convection uses up a lot of energy too and also counters the idea of radiative heat transfer as a big ticket item because «hot» CO2 molecules only remain so for a brief fraction of a second before they collide with N2 or O2 to warm that localised parcel of air; which then rises to attain equilibrium T somewhere higher and at a COLDER temp so no rad Transf!!!
«The dual wave and particle nature of radiation is recognised, but it is considered more appropriate, and indeed necessary, for an understanding of radiative heat transfer to consider the frequencies and intensities associated with the wave nature of radiation, for only then can the one - way transfer of heat be described and quantified in a meaningful manner.»
In air, the radiative heat transfer flux for 0.9 emissivity steel only exceeds natural convection at c. 100 deg C. For aluminium it's about 300 deg C. Check any of the standard engineering texts, e.g. McAdam «Heat Transfer» to confirm (it's in the tables of combined heat transfer coefficienheat transfer flux for 0.9 emissivity steel only exceeds natural convection at c. 100 deg C. For aluminium it's about 300 deg C. Check any of the standard engineering texts, e.g. McAdam «Heat Transfer» to confirm (it's in the tables of combined heat transfer coeffitransfer flux for 0.9 emissivity steel only exceeds natural convection at c. 100 deg C. For aluminium it's about 300 deg C. Check any of the standard engineering texts, e.g. McAdam «Heat Transfer» to confirm (it's in the tables of combined heat transfer coefficienHeat Transfer» to confirm (it's in the tables of combined heat transfer coeffiTransfer» to confirm (it's in the tables of combined heat transfer coefficienheat transfer coeffitransfer coefficients).
The dynamics of the system are governed by the lapse rate which is «anchored» to the ground and whose variations are dependent not only on convection, latent heat changes and conduction but also radiative transfer.
There is some conduction at the surface from the atmosphere, and there is some radiative heating at, and just below the surface, but that heat will only transfer through the water itself through convection.
It is not «conduction» but exchange of radiation; if you keep your hands parallel at a distance of some cm the right hand does not (radiatively) «warm» the left hand or vice versa albeit at 33 °C skin temperature they exchange some hundreds of W / m ² (about 500 W / m ²) The solar radiation reaching the surface (for 71 % of the surface, the oceans) is lost by evaporation (or evapotranspiration of the vegetation), plus some convection (20 W / ²) and some radiation reaching the cosmos directly through the window 8µm to 12 µm (about 20 W / m ² «global» average); only the radiative heat flow surface to air (absorbed by the air) is negligible (plus or minus); the non radiative (latent heat, sensible heat) are transferred for surface to air and compensate for a part of the heat lost to the cosmos by the upper layer of the water vapour displayed on figure 6 - C.
First, radiative heat transfer will only occur with the approximately 2 % of the gaseous molecules that are IR active.
Therefore it is only the net energy flows which need be considered when estimating the radiative heat transfers in the diagram.
According to Lindzen, if there were only radiative transfer of heat, that 323w / m2 of backradiation would create a greenhouse effect of 77C instead of 15C [288K]; the greenhouse effect is only working at less than 25 % of its potential.
Radiative heat transfer is not the only mechanism, and some of what is observed today is not explained: on another thread is a discussion of clouds.
Or it may be that as an instantaneous solution to radiative transfer, HITRAN is ok, but to the question of non-instantaneous energy transfer from the surface to the TOA which necessarily includes convection and transfer of energy by latent heat of vaporisation and more... then it only tells part of the story.