Knut Ångström (the son of) did some observations by himself on the top of mount Teide on the Island of Tenerife. He constructed a double tube of which one was filled with CO2 and measured the difference in absorption in solar rays.He did not measure any difference.
Here is the explanation why Knut Angstrom could not detect a CO2 effect in the solar spectrum: There hardly is any CO2 absorption in the solar spectrum. Angstrom wrongly concluded that the CO2 spectrum is saturated and this theory is still hunting the climate Internet fora.
This straightforward application of the Lambert-Beer absorption law shows how the absorption of CO2 increases through the sidelobes.
In the second part of the 1900 paper Ångström cites two observed absorption CO2 values by Koch: For an optical path of 30 atm cm 10% absorption and for 20 atm cm 9.6% absorption, which would extrapolate to 16%
for the entire atmosphere (250 atm cm co2) If we compare that in a graph we notice the following:
1) Ångström rightly criticised the extreme high co2 absorption values of Arrhenius 1896
2) Arrhenius confirmed (!) the observations by Ångström in 1901
Full scan of Annalen der Physik Bd 3. 1900, p720-732.
page 720 721
page 722 723
page 724 725
page 726 727
page 728 729
page 730 731
In the same paper he also presented a very modern CO2 absorption spectrum.
modified 28 june 2007