The BOM

The following comes from a publication put out by The BOM. The BOM is otherwise known as The Bureau of Meteorology,  Australia’s national weather, climate and water agency.

http://www.bom.gov.au/info/GreenhouseEffectAndClimateChange.pdf

The greenhouse effect

The earth is not, of course, the simple solid ball we have assumed so far. It is surrounded by a thin layer of air (Figure 3), held to it by gravity and consisting almost entirely of nitrogen (78% by volume) and oxygen (21%).

These major constituents are essentially transparent to both the incoming solar (short wave) radiation and the infrared (long wave) radiation emitted upward from the earth’s surface. There is also a number of minor constituents, especially water vapour and carbon dioxide, which are largely transparent to the incoming solar radiation, but strongly absorb the infrared radiation emitted from the ground.

This is misleading – a large proportion of incoming solar radiation is absorbed and/or reflected by the atmosphere. It is NOT “essentially transparent”. Figure 7 below suggests that only half of the incident solar radiation is absorbed by the ground.

Figure 4 illustrates the absorption spectra for the two most abundant of these radiatively active gases. The most significant is water vapour, which is not well mixed and may vary locally from less than 0.01% by volume to more than three per cent. The next most abundant is carbon dioxide (CO2) which has a long lifetime in the atmosphere and is well mixed around the globe. Other important trace gases are methane, nitrous oxide, ozone and anthropogenic halocarbon compounds, such as the ozone-depleting chlorofluorocarbons and hydrofluorocarbons.

The radiation absorbed by these gases is re-emitted in all directions, some back toward the surface leading to a net warming of the surface.

The Scientists at the BOM believe that radiation emitted by a cold surface (the GH gasses in the atmosphere) can increse the temperature of the warmer Earths surface! I expect they believe hail stones and snow can also warm up the surface of the Earth – this is basic thermodynamics!

Through what is widely, but inaccurately, referred to as the greenhouse effect, these so-called greenhouse gases trap heat in the near surface layers of the atmosphere and thus cause the earth’s surface to be considerably warmer than if there were no greenhouse effect. The mechanism of the natural greenhouse effect and its impact on the earth’s surface and atmospheric temperatures is shown schematically in Figure 5. In the left panel, for the hypothetical situation of no greenhouse gases, the ground heats up until it reaches the temperature at which the outward radiation to space equals the incoming solar radiation, i.e., the planetary radiative temperature, TO, of -18°C (255K) noted earlier.

By conveniently leaving out a term in the Stefan-Boltzmann equation they get this figure- it is meaningless and erroneous. This is basic Physics, how can they get this so wrong?

In the more realistic situation in the middle panel, the greenhouse gases in the atmosphere absorb some of the outgoing terrestrial (infrared) radiation and re-radiate infrared energy in all directions. There is thus now more radiant energy (short wave plus long wave) being absorbed by the ground and so it heats up further, by some tens of degrees, until the upward infrared emission just balances the total downward infrared and solar radiation at a surface temperature of TS.

Once again, the cold radiation can heat up the surface by some tens of degrees”!

With a normal distribution of greenhouse gases in the atmosphere, and notwithstanding the many other physical processes that come into play, this leads to a vertical temperature profile in the atmosphere and ocean taking the general form of the solid curve in the right panel of the diagram. The difference (TS-TO) is a measure of the greenhouse effect at the earth’s surface.

There seems to be an implication here that GH gasses cause the ‘lapse rate’ in out atmosphere! (The lapse rate is defined as the rate at which air temperature falls with increasing altitude.)

Here is figure 5 :

Figure 5

The middle panel is meant to show an increase in the temperature of the Earth due to downward radiation from GH gasses! If you look carefully you will see that the downward radiation arrow is equal to the upward radiation arrow directly above it at the top of the page in the middle panel. Remember that as we look at the next diagram.

One plus One equals Three

If you look at the right hand side of the figure you will see the downward radiation from the GH gasses in the atmosphere. The value of this radiation is 329 W/m2 almost as mush as the incident solar radiation (340 W/m2). But there must be an equal amount upward. The caption says the atmosphere radiates infrared radiation in all directions. Where is the equal upward radiation  figure?

If 329 W/m2 were radiated from the atmosphere to space we would have far mor energy leaving the Earth then received!

This can not be! How can this figure be produced unquestioned by “leading” scientists. Who reviewed this? Why is it still being used!

Are these same people advising our Government!

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