2. The 'greenhouse effect' misnomer
2.1. What is meant by greenhouse effect?
The term 'greenhouse effect' is meant to convey the notion that excess production of CO2 by fossil fuel burning and other so-called GHGs like methane and water, and their accumulation in the troposphere, results in a radiation imbalance; the GHGs retain reflected or incident photons associated with solar radiation, decreasing the amount of heat that the Earth releases to space, and releasing it at ground level as IR during nighttime. This supposedly creates a thermal anomaly, ie 'man-made global warming'.
2.2. What really is a greenhouse?
A greenhouse is an enclosed environment for plant growth, where the enclosure blocks air circulation and serves as a filter for photons associated with solar radiation, blocking most UV and thus 'letting through', so to speak, some visible and IR photons. These photons and that filtered radiation transfer their energy to a water vapour-saturated enclosed air volume, or to photosynthetic plants that, by absorbing them (ie in their presence), fix CO2 and uptake water-vapour to release oxygen.
2.3. Does the functioning of a greenhouse explain the so-called 'greenhouse effect'?
Were the analogy to be valid, it should. But it doesn't, not even in principle. The reason is that most plants do not release CO2 in response to solar radiation, filtered or not. Plants are not, therefore, the analogue of man-made fossil-fuel burning. It is only during nighttime (or in the dark) that most plants respire, reverting the daytime process by reducing (fixing) oxygen and releasing CO2, heat and water vapour. But this occurs not in the presence of sunlight or because of the atmospheric interaction with it (as is the case for the claimed 'greenhouse effect'), but in its absence. It is true that some plants (called C3 plants) will photorespire, that is, in the presence of photons associated with sunlight, they will not fix CO2, but instead consume oxygen and release CO2. However, even these plants only do so when the concentration of CO2 is less than 50 ppmv, thus invalidating even an analogy between the so-called 'greenhouse effect' and a greenhouse of C3 plants.
Moreover, a greenhouse only becomes warm and humid because it has man-made walls blocking both wind currents and the escape of heat and humidity, and because of man's action of watering and humidifying it during the daytime.
So the term 'greenhouse effect' is a total misnomer: greenhouses during the day generate oxygen, not CO2, and fix CO2, not oxygen; greenhouses during the day absorb water, they don't release it; greenhouses during the day trap heat because of their walls, not because of an absorptive ground like asphalt, or a reflective environment like concrete, glass and metal; greenhouses allow IR photons in and block UV because of artificial walls and ceilings made of glass or plastic - not so the atmosphere, which has no such protective enclosure and is perfectly capable of 'transmitting' UV photons associated with solar radiation or produced in situ by physico-chemical interactions of acidic water vapour and free-radicals, particularly in the lower troposphere over urbanized land surfaces.
The only parallel between a greenhouse and the so-called 'greenhouse effect' is that, at nighttime, a greenhouse (ie its plants) releases CO2 and water vapour - both of which serve as latent heat storage molecules which can convert their kinetic states, including their latent heat, into IR photons (sensible radiant heat). It is only the nighttime heating that serves as a kind of parallel. But this parallel is not driven by solar radiation nor by man's action, nor by a combination of the two. Plants do this without need for man, and only in the absence of that radiation or its photon byproducts.
Furthermore, in the open atmosphere, the 'enclosure' is a dynamic process - the 'enclosing' occurs at the transitions between troposphere and stratosphere, between stratosphere and ionosphere, where energy and chemical fluxes going out into space and coming from space incessantly interact with the Earth. CO2 is not impeded from rising in the atmosphere, nor is water vapour, precisely because there are no rigid enclosures stopping them. So, the so-called 'greenhouse effect' begs the very question - what is it that causes the trapping of water vapour and CO2 at ground level? And why do man's action and solar radiation combine to intensify it? The very name of the effect explains nothing. It is, in fact, a sordid misnomer that unconsciously insinuates that plants are, like man, toxic polluters.
Lastly, but not least, just because a gas can release IR photons one should not indiscriminately call it a 'greenhouse gas'. The atmosphere is warmed by solar radiation byproducts. In the context this warming, qua radiative release of sensible heat, IR photons play a secondary role with respect to the warming caused by UV photons. That's right, even the term warming has suffered this dissonance - it pretends to designate only 'heat photons' and their effect, but it has the pretension to mean sensible heat in general, and even to serve as such like an index of energy, of total energy. Three errors in one. And all three errors put into evidence the lack of understanding that all blackbody photons, optical or not, are a source of radiant sensible heat. In fact, most such radiant sensible heat is generated as blue light and IR photons, not by CO2 or water vapour, but by the atmospheric cycle that forms oxygen from ozone together with the formation of water from atomic oxygen, protons and electrons. The joint formation of oxygen and water are the main natural processes releasing heat in the atmosphere. And plants, by the way, are what absorbs CO2 and regenerates that oxygen under the action of solar radiation.
Now, days with little air movement, characterized by low-altitude thick cloud cover, do indeed trap the energy of longer wavelength photons, and filter out UV and most visible photons associated with incoming solar radiation. Such days present an analogy with the effect of the translucent walls of a greenhouse, which filter solar radiation and keep heat and humidity from rising and escaping. But these effects in nature are natural constraints of low-pressure (cyclonic) systems, specifically, of their barimetrically stable center (it is not only hurricanes that have a nearly quiet 'eye' zone). One can speak of high-pressure (anticyclonic) systems with analogous properties of trapping heat and humidity, but this phenomenon is due, instead, to the particulates of man-made pollution (haze, not cloud cover) that trap water vapour and heat. Yet, the action of these pollutants is neither defined by, nor limited to, this trapping of water vapour and heat - since they introduce into the oceans and the atmosphere a whole other set of chemistries which suppress oxygen and trap other forms of energy besides radiant sensible heat.