Greenhouses work as follows: radiation from the sun heats up the objects inside, which in turn warm the air in contact with them. This warm air cannot escape because it is contained by the glass, and is trapped inside. On a clear night the temperature in the greenhouse falls quickly due to radiation through the glass. That is why it is necessary to have blinds inside the roof to prevent this night-time radiation.
The so-called “greenhouse effect” is ascribed to absorption, at night, of radiation from the surface of the earth by greenhouse gases and its subsequent re-radiation in all directions ie 50% of the captured radiation is returned back towards the surface of the earth. However, given that all the carbon dioxide in the atmosphere would form a layer less than 4 metres deep, and that carbon dioxide absorbs infra red radiation in just a few narrow frequency bands, I would like to see calculations which show that this process can have any significant effect.
If the planet is warming, there is a more plausible explanation. We all know that during the day, it is cooler if it is cloudy, and that at night, it is cooler if the sky is clear. Clouds reflect radiation. When, horror of horrors, you travel in an aircraft, it is dazzlingly bright when you are above the clouds. Water droplets in clouds act like cats eyes in the road. So the finger of suspicion should point to an increase in night-time cloud cover and/or a decrease in daytime cloud cover. What might have caused this? The most likely reasons are deforestation and a change in agricultural practices such as irrigation. The Aral Sea almost disappeared because of irrigation. That would have had some effect on the climate.
The so-called “greenhouse effect” is ascribed to absorption, at night, of radiation from the surface of the earth by greenhouse gases and its subsequent re-radiation in all directions ie 50% of the captured radiation is returned back towards the surface of the earth. However, given that all the carbon dioxide in the atmosphere would form a layer less than 4 metres deep, and that carbon dioxide absorbs infra red radiation in just a few narrow frequency bands, I would like to see calculations which show that this process can have any significant effect.
If the planet is warming, there is a more plausible explanation. We all know that during the day, it is cooler if it is cloudy, and that at night, it is cooler if the sky is clear. Clouds reflect radiation. When, horror of horrors, you travel in an aircraft, it is dazzlingly bright when you are above the clouds. Water droplets in clouds act like cats eyes in the road. So the finger of suspicion should point to an increase in night-time cloud cover and/or a decrease in daytime cloud cover. What might have caused this? The most likely reasons are deforestation and a change in agricultural practices such as irrigation. The Aral Sea almost disappeared because of irrigation. That would have had some effect on the climate.
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