Intensive reflection of sunlight at sunrise/sunset I would like to ask about the phenomenon, which always occurs near sunrise/sunset.

If I could be more precise. When Sun goes down its strong reflection is to be spotted usually at trees, but also other objects. It's expressed well when dealing with long-distance photography, especially when the solar disk is enormous in comparison to a distant tree. It looks like the trees (or other objects) are optically "on fire". It's best visible shortly after sunset (literally 1-2 seconds after the sun's disk disappears beyond the horizon).

Is anyone able to explain this phenomenon or even better - post some links, and sources where I could read more about it?
 A: I believe this is an optical effect that has long interested physicists, astronomers, and poets, as discussed John Hardwick's 2020 article "Sunrise on the pines" in the journal Applied Optics. Mentioned by Shakespeare (Richard II, Act iii, sc. 2, line 1450),
the first known scientific description was in an 1832 letter from Louis Necker to David Brewster.
Great Irish physicist John Tyndall "was ambiguous as to the origin of the phenomenon likening it to the diffractive glare around the sun but also explicitly referring to reflection from the pine needles’ smooth surfaces." Others believed it to be specifically due to diffraction from the narrow pine needles,
and Jacques Babinet cited it as example of the optical diffraction theorem that we now know as Babinet's principle.
Marcel Minnaert also described it as a diffractive phenomena in his book "The nature of light & colour in the open air". But François Folie was skeptical. Any physicist or astronomer wandering the Alps around sunset or sunrise seems to have been at high risk of being nerd sniped by the phenomenon.
According to Hardwick, it has not been resolved how much of the effect is diffraction and how much is due to low angle specular reflection.  The problem with diffraction around pine needles is that they are not thin enough to produce the angular dispersion of up to several degrees that has sometimes been reported. The problem with simple models of specular reflection is the opposite, the reflection wouldn't fall off as fast as observed.  I would guess both processes contribute, depending on the details of what is doing the diffracting/scattering/reflecting. You mention observing the effect for objects other than trees, and such observations could be very helpful for disentangling what is going on.
Necker's original observation was on the Salève near Geneva, so this might be an interesting after-hours research project for some physicist at CERN.
Note: If you don't have access to the paywalled Hardwick article, you can get the contact information for the author by clicking on "Author Information" on the article landing page.
