Thermometers cannot measure precisely air's temperature
The air temperature measurements by thermometers sheltered in the standardized screens are not air temperature precise measurements. These measurements and the data they provide are not reliable for the long time scale very small climate changes estimation.
There are differences in measurements from site to site and from latitude to latitude.
There are differences at the sites with a high amplified diurnal temperature cycle, or with days with strong winds or without any air movement at all.
When I started this work I knew there should be differences and ill corrections in measuring the outdoors air temperature, but what I am finding happens to be overwhelming.
It is not like it was for the two last centuries of outdoors air temperature measurements.
Climatologists were monitoring temperatures all right, but back then there was not the now day’s persistent need in very exact and very precise temperature data. Because for evaluating 0,1°C per decade Global Warming we need to have very precise and very much reliable temperature data.
But in any case, air temperature measurements cannot be considered as the solid prove of earth’s climate warming.
Air is very thin and does not accumulate much energy compared with the oceanic waters and the land masses.
For two centuries we were accustomed measuring outdoors air temperature with indoors thermometers. It was a scientific fast forward break thru at the time.
But it is not so anymore.
When multiple precise temperature measurements data involved, finally the air temperature measurements are not capable to serve the case.
Actually the conventional thermometer with a bulb or with a resistance doesn’t measure the air temperature.
The thermometer with a bulb or with a resistance measures the radiative energy of its surroundings.
It is Ok when it is cold, the thermometer shows lower temperatures. When it is freezing, the thermometer shows below zero.
And when it is hot – it is hot for the thermometer too.
All this happens because thermometer consists from matter. Thermometer itself is made from a matter.
As it is said by science the matter is in radiative equilibrium with its surroundings.
When a disturbance in this equilibrium takes place, for instance when we take thermometer from the cold outside in the warm room the thermometer will gradually adjust to the new radiative conditions.
As every other item made of matter does.
The temperature thermometer shows will gradually rise, until thermometer reaches the new radiative equilibrium with its surroundings.
Then the temperature it shows stabilizes.
But this entire time thermometer doesn’t measure the air’s temperature.
It shows us the differences in radiative energy, in the matter from which thermometer is made, that absorbed or emitted.
Radiative Energy Transfer Intensity is the dicisive factor in Thermometer Temperature Measurements
When the conventional thermometer was invented it happened in an indoors workshop.
The newly made Thermometer was a great invention at the time.
It made it possible to measure the heat intensity.
When it was cold Thermometer measured how much cold it was.
And when it was hot Thermometer measured how much warm it was there.
They eventually took Thermometer outdoors; they took it out in the open place.
When under the sun’s irradiation Thermometer showed a much higher temperature.
What they decided then was that when Thermometer is put in the shade, it measures the air temperature, because when on sun it gets complement heated by the sun’s rays.
So, they concluded, if thermometer is properly insulated from the direct sun rays it would measure exclusively only the air’s temperature.
Of course they didn’t know about the infrared radiation the matter emits all the time in accordance to the Stefan-Boltzmann Law.
So they had thermometers indoors and it was decided they measured the indoors air temperature.
And the workshops where the basic laws of thermodynamic were discovered in also were indoors laboratories.
They had not a problem then. They had no difficulties discovering the fundamental laws of ideal gasses because in the indoors laboratories the air was in the constant equilibrium with the inside of the walls and all the other surroundings.
Of course scientists performed their precise measurements experiments with the gasses extension behind the closed doors.
The doors were closed so no one could disturb the very accurate measurements with ideal gasses temperatures they did at the time.
At the party with friends take out from your inner pocket an indoor air measuring thermometer and put it on the desk.
Ask then your friends a very simple question: “What temperature does thermometer shows?”
It is a very amusing joke, you will be surprised with answers you will have.
I also used to take out the indoors thermometer to measure the air temperature in the shade on my balcony.
I also used to measure the air temperature at cold winter nights in the open on the balcony.
Each time I gave it some time for the thermometer’s temperature to adjust to the outside temperature, as I thought at the time, to adjust to the outside air temperature, since thermometer was at the room temperature when it was taken out.
So here we are.
There is another issue in measuring air temperature with the thermometers sheltered in the standardized Stevenson’s screens.
This very important issue has to do with the adjustment time needed for the thermometer to respond to the changes of the (I am not saying air temperature only) surroundings temperature.
Thermometers what they are doing is measuring their surrounding’s thermal conditions from the inside of the standardized shelters.
Look what I finally found out about measuring the temperature of the outside air from the measuring stations.
The air temperature measurements by thermometers sheltered in the standardized screens are not air temperature precise measurements.
These measurements and the data they provide are not reliable for the long time scale very small climate changes estimation.
It happens because the thermometer in the shade does not measure the temperature of the air.
The Sun may not see it directly, but even the shelter itself emits infrared radiation.
And the thermometer, on the other hand, emits its own infrared radiation too. In general, matter is constantly emitting infrared radiation.
So the thermometer, like any other object, tries to balance thermally with its overall environment.
Thermometer shows the temperature at which it has been warmed, and not the temperature of the surrounding air, thermometer is in a thin direct contact with.
Air basically acts as an insulator than a transmitter of energy, so air is not capable to “write” its actual temperature in the thermometer’s display.
This is because by radiation the thermometer is heated and cooled much more intensely than with its epidermal contact with the air.
Radiative equilibrium temperature
It is very hot in the sauna.
When sauna is well warmed the temperature there may exceed 80 °C.
No one gets burned though from the hot air at the temperature 80 °C in saunas. The body’s skin does not get burned from the 80 °C hot air inside the sauna.
It has to do with the energy transfer from a very thin matter as the air is to the very dense solid body.
The same is with the conventional thermometer. There is very weak energy transfer from the thin air to the solid bogy of the thermometer.
Or, when the air is colder, there is very weak energy transfer from thermometer’s body to the air, so thermometer can not get cooled fast enough to deliver the cold air’s actual temperature.
It is very hot in summer time. The instructions are to stay indoors at the most hot midday hours.
To save electricity the advice is to use an air ventilator instead of an air conditioner. It is a good advice. This way we may save us a lot of electrical energy.
When under the air flow from ventilator we experience a very pleasant cooling sensation. It is the air’s lower temperature, compared with the indoors surroundings, that cools our skin.
When the air strikes the bodies, with some higher velocity, the energy transfer from the solid body to the very much thinner substance as air is intensifies.
And this energy transfer from a solid body to a much thinner air physical phenomenon we enjoy as a pleasant cooling on our skin. But this process involves a vigorous air flow produced by ventilator.
Let’s do a simple experiment:
We shall take a box; say a camera with strong walls, strong enough to withstand the outside atmospheric pressure of 1 bar.
And we are putting in the center of the box a piece of wood. We hang the piece of wood in the center of the box’s volume, so the piece won’t get in any contact with the box’s walls, top or bottom.
Or, yes, it is a special box or camera, we are able to suck out all the air from inside the box and create inside a very-very deep vacuum.
After that a radiative equilibrium will take place. The piece of wood has not any contact with the surrounding it box.
So there is only a radiative energy transfer from the box’s walls, top and bottom towards the wooden piece and back to the walls, top and bottom.
And it is not necessary should be a piece of wood we hang in the center of the box. The same will do if we hang there a piece of some plastic or metallic item. Anything will do for our experiment, anything that consists of a solid matter will do.
We can have hang there in the air free, since we have sucked out all the air and created a very-very deep vacuum, we can have hang in the center of the box a conventional thermometer, or a thermometer with an electrical resistance.
It also will come in radiative equilibrium with its surroundings in the box’s center.
Let’s now put a wooden item or of any other material in the Stevenson’s screen (Stevenson screen or instrument shelter).
What would be the temperature of that item, no matter what material it is made from? Would it, after a while, after a sustainable time to have it adjusted and to get in radiative equilibrium with the surrounding the item Stevenson’s screen walls, bottom and top, would this item, no matter what material it is made from, have the temperature of the air getting in and out in the Stevenson’s screen from the double louvers?
It is necessary to underline here that the air is getting in the Stevenson’s screen, to have measured its temperature, thru the double louvers via natural circulation.
We have to answer these two questions now:
Do the walls, the bottom and the top in the Stevenson’s screen have the incoming air’s temperature?
No, they do not.
Is the conventional thermometer with a bulb or with an electrical resistance capable to deliver the necessary for the climate change estimation precise air’s temperature measurements?
No, it does not.
What we are sure of is that a conventional thermometer measures its own temperature.
Indoors the conventional thermometer is not capable to deliver the air’s temperature because thermometer is in radiative equilibrium with its surroundings.
On the other hand the air indoors is not in a radiative equilibrium with its surrounding. The indoors air is as transparent to the infrared radiation as the outdoors air is.
The actual air temperature is few degrees oC below zero already
Air temperature measuring thermometers in standardized Stevenson's shelters with natural air circulation are indicating their own temperature.
The liquid-in-glass thermometers show the temperature the liquid has acquired, and the resistance thermometers show the temperature the resistance has acquired.
They do not show the air's temperature, because they are not capable to do so.
These thermometers were good enough two centuries ago, when they showed it was colder or warmer.
The data collected by these measurements cannot be used for precise climate changes monitoring.
First they are not calibrated to measure air's temperature in standardized Stevenson's shelters with natural air circulation.
Second the inside shelters walls infrared radiation is what these thermometers are capable to measure.
Third the energy transfer to the thermometers from and to the natural circulated air is very slow and weak process compared with the inside shelters walls infrared radiation towards thermometers.
Remember how the Celsius scale was invented.
The glass tube with bulb. The bulb was dipped in the melting ice - it was for
= 0 oC.
Then the bulb was dipped in the boiling water - it was for
= 100 oC.
Now, has it been dipped the thermometers' bulb in the melting ice when it shows
= 0 oC air temperature ?
No, of course not. When thermometer shows
= 0 oC air temperature, the actual air temperature is few degrees oC below zero already.
The faster a planet rotates (n2>n1) the higher is the planet’s average (mean) temperature T↑mean:
Tmin↑→ T↑mean ← T↓max