Measurement started when the thermometer was exposed. As you can see in the video at this link, the temperature started to rise from 11.24 ° C and then fluctuated between 11.26 ° C to 11.30 ° C throughout the measurement period. At the moment when I approached to the system to cover it from the moonlight, the temperature was 11.26 ° C (Footsteps and the sound of moving the plate can be heard at about 10 minutes and 30 seconds of the movie). After covering, the temperature was 11.33 ° C. Then, when I went away, it dropped to 11.24 ° C, which was probably caused by air movement, and then raised oscillating to 11.38 ° C at the end of this part of the measurement. Then I unhid the thermometer (about 20 minutes 40 seconds at the movie) and the temperature began to drop down from 11.36 ° C to 10,81 ° C at the end of this measurement section (30 minutes 20 seconds you can hear the steps at the film and the sound of moving the plate). I moved the plate again to cover the thermometer and walked away. The plate was in the same place where it was during the first hiding cycle, but I noticed that the Moon has moved in the sky and the plate did not cover the tip of the thermometer anymore. Moonlight was falling on the thermometer. If there was any movement of air cooling the thermometer, then, as in the first cycle, the plate should stop it. Before there was an increase in temperature but that time a fall. The temperature dropped oscillating from 10.80 ° C to 9.88 ° C. The last recorded measurement is 10.05 ° C when I was turning the camera off. The increase in temperature probably was caused by my presence near the research set. I decided to repeat the measurement. I made a second movie, but the battery in the camera was exhausted and I was able to register only one full cycle. The film can be seen at this link. As you can see in the movie when the thermometer was covered, the temperature has increased from 10,08 ° C to 10,31 ° C. During the exposure for moonlight it dropped from 10.36 ° C to 9.83 ° C.
And what conclusions can be drawn from the experiment?
This experiment suggests that there is some factor not related to convection, by which some people try to explain the phenomenon of the moonlight cooling, which causes the objects to cool down when the moonlight hits them. It seems that the cooling factor comes from the side of the Moon. The aluminum plate holds it back.
So what can it be?
Visible light does not heat or cool objects. But what about infrared radiation?
The website livescience.com informs us:
"Everything with a temperature above about 5 degrees Kelvin (minus 450 degrees Fahrenheit or minus 268 degrees Celsius) emits IR radiation."
And what about Moon's temperature?
The space.com explains:
"When sunlight hits the moon's surface, the temperature can reach 260 degrees Fahrenheit (127 degrees Celsius). When the sun goes down, temperatures can dip to minus 280 F (minus 173 C)."
My guess is that the Moon warms up and colds only at the outermost layer to a depth of several dozens, maybe several hundreds meters. We do not know so much about Moon's interior. Only hypothesis. It could be that the entire interior of the Moon has a constant average temperature of around -23 ° C. We know from the pictures of the surface of the Moon that it has a gray color. So we can treat the whole Moon as a gray body. The maximum intensity of the gray body radiation (Wien's displacement law) determines the identical pattern as for the black body, that is, the shorter wave the higher temperature - inverse proportion. Stefan - Boltzmann's law is almost identical to that for a black body, that is, the power emitted by the surface unit is proportional to the fourth power of temperature. For the temperature of -23 ° C (150.15 K) the most of energy the Moon radiates in the infrared wave form with wavelength 0.00193 cm, that is 1.93 x 10-5 m.
From everyday experience, we know that if we have, for example, a piece of ice, we do not have to touch it to feel its cold. It is enough to bring a hand closer. If we hold our hand near to the ice piece and feel its coolness, it is not a convection or some other flow of cold air, but we sense the infrared radiation of the object. So we can hypothesize that the cooling factor for the thermometer in the experiment described above is infrared radiation with a wavelength of 1.93 x 10-5 m corresponding to the temperature of -23 ° C. If the hypothesis is true, the Moon should cool the objects also in other phases in addition to the Full Moon. And even the result should be better, because measurement will be less distorted by the warm Moon's surface. The best results should be around the new moon.