Work on glaciers alerted Tyndall to the research of de Saussure into the heating effect of sunlight, and the concept of Fourier, developed by Pouillet and William Hopkins; that heat from the sun penetrates the atmosphere more easily than "obscure heat" (infrared)  "terrestrial radiation" from the warmed Earth, causing what we now call the greenhouse effect.
In the spring of 1859 Tyndall began research into how thermal radiation, both visible and obscure, affects different gases and aerosols.
He developed differential absorption spectroscopy using the electro-magnetic thermopile devised by Melloni.
Tyndall began intensive experiments on 9 May 1859, at first without significant results, 
 then improved the sensitivity of the apparatus and on 18 May wrote in his journal "Experimented all day; the subject is completely in my hands!"
On 26 May he gave the Royal Society a note which described his methods, and stated "With the exception of the celebrated memoir of M. Pouillet on Solar Radiation through the atmosphere, nothing, so far as I am aware, has been published on the transmission of radiant heat through gaseous bodies.
We know nothing of the effect even of air upon heat radiated from terrestrial sources."

On 10 June he demonstrated the research in a Royal Society lecture, noting that coal gas and ether strongly absorbed (infrared) radiant heat, and his experimental confirmation of the (greenhouse effect) concept; that solar heat crosses an atmosphere, but "when the heat is absorbed by the planet, it is so changed in quality that the rays emanating from the planet cannot get with the same freedom back into space.
Thus the atmosphere admits of the entrance of solar heat; but checks its exit, and the result is a tendency to accumulate heat at the surface of the planet."

Tyndall's studies of the action of radiant energy on the constituents of air led him onto several lines of inquiry, and his original research results included the following:
Tyndall explained the heat in the Earth's atmosphere in terms of the capacities of the various gases in the air to absorb radiant heat, in the form of infrared radiation.
His measuring device, which used thermopile technology, is an early landmark in the history of absorption spectroscopy of gases.
He was the first to correctly measure the relative infrared absorptive powers of the gases nitrogen, oxygen, water vapour, carbon dioxide, ozone, methane, and other trace gases and vapours.
He concluded that water vapour is the strongest absorber of radiant heat in the atmosphere and is the principal gas controlling air temperature.
Absorption by the other gases is not negligible but relatively small.
Prior to Tyndall it was widely surmised that the Earth's atmosphere warms the surface in what was later called a greenhouse effect, but he was the first to prove it.
The proof was that water vapour strongly absorbed infrared radiation.
Relatedly, Tyndall in 1860 was first to demonstrate and quantify that visually transparent gases are infrared emitters.

He devised demonstrations that advanced the question of how radiant heat is absorbed and emitted at the molecular level.
He appears to be the first person to have demonstrated experimentally that emission of heat in chemical reactions has its physical origination within the newly created molecules (1864).
He produced instructive demonstrations involving the incandescent conversion of infrared into visible light at the molecular level, which he called calorescence (1865), in which he used materials that are transparent to infrared and opaque to visible light or vice versa.
He usually referred to infrared as "radiant heat", and sometimes as "ultra-red undulations", as the word "infrared" did not start coming into use until the 1880s.
His main reports of the 1860s were republished as a 450-page collection in 1872 under the title Contributions to Molecular Physics in the Domain of Radiant Heat.

In the investigations on radiant heat in air it had been necessary to use air from which all traces of floating dust and other particulates had been removed.
Work on glaciers alerted Tyndall to the research of de Saussure into the heating effect of sunlight, and the concept of Fourier, developed by Pouillet and William Hopkins; that heat from the sun penetrates the atmosphere more easily than "obscure heat" (infrared)  "terrestrial radiation" from the warmed Earth, causing what we now call the greenhouse effect. In the spring of 1859 Tyndall began research into how thermal radiation, both visible and obscure, affects different gases and aerosols. He developed differential absorption spectroscopy using the electro-magnetic thermopile devised by Melloni. Tyndall began intensive experiments on 9 May 1859, at first without significant results, 
 then improved the sensitivity of the apparatus and on 18 May wrote in his journal "Experimented all day; the subject is completely in my hands!" On 26 May he gave the Royal Society a note which described his methods, and stated "With the exception of the celebrated memoir of M. Pouillet on Solar Radiation through the atmosphere, nothing, so far as I am aware, has been published on the transmission of radiant heat through gaseous bodies. We know nothing of the effect even of air upon heat radiated from terrestrial sources."
On 10 June he demonstrated the research in a Royal Society lecture, noting that coal gas and ether strongly absorbed (infrared) radiant heat, and his experimental confirmation of the (greenhouse effect) concept; that solar heat crosses an atmosphere, but "when the heat is absorbed by the planet, it is so changed in quality that the rays emanating from the planet cannot get with the same freedom back into space. Thus the atmosphere admits of the entrance of solar heat; but checks its exit, and the result is a tendency to accumulate heat at the surface of the planet." 
Tyndall's studies of the action of radiant energy on the constituents of air led him onto several lines of inquiry, and his original research results included the following:
Tyndall explained the heat in the Earth's atmosphere in terms of the capacities of the various gases in the air to absorb radiant heat, in the form of infrared radiation. His measuring device, which used thermopile technology, is an early landmark in the history of absorption spectroscopy of gases. He was the first to correctly measure the relative infrared absorptive powers of the gases nitrogen, oxygen, water vapour, carbon dioxide, ozone, methane, and other trace gases and vapours. He concluded that water vapour is the strongest absorber of radiant heat in the atmosphere and is the principal gas controlling air temperature. Absorption by the other gases is not negligible but relatively small. Prior to Tyndall it was widely surmised that the Earth's atmosphere warms the surface in what was later called a greenhouse effect, but he was the first to prove it. The proof was that water vapour strongly absorbed infrared radiation. Relatedly, Tyndall in 1860 was first to demonstrate and quantify that visually transparent gases are infrared emitters.
He devised demonstrations that advanced the question of how radiant heat is absorbed and emitted at the molecular level. He appears to be the first person to have demonstrated experimentally that emission of heat in chemical reactions has its physical origination within the newly created molecules (1864). He produced instructive demonstrations involving the incandescent conversion of infrared into visible light at the molecular level, which he called calorescence (1865), in which he used materials that are transparent to infrared and opaque to visible light or vice versa. He usually referred to infrared as "radiant heat", and sometimes as "ultra-red undulations", as the word "infrared" did not start coming into use until the 1880s. His main reports of the 1860s were republished as a 450-page collection in 1872 under the title Contributions to Molecular Physics in the Domain of Radiant Heat.
In the investigations on radiant heat in air it had been necessary to use air from which all traces of floating dust and other particulates had been removed. 
John Tyndall