In short the wavelength of sunlight that promotes vitamin D in the skin is 290 - 300 nm, which is in the UVB spectrum. Due to the angle of the sunlight in the morning and evening, nearly all the sun that hits your body is in the UVA spectrum - 315 - 400nm.

UVA light produces ZERO vitamin D. None whatsoever. As such sunlight in the morning and evening has no effect on vitamin D in the human body. HOWEVER! UVB UVA radiation does raise your risk of skin cancer due to damaging your DNA which can lead to mutations and then to cancer. So UVB UVA does nothing for vitamin D levels while also raising your skin cancer risk.

BAck to the sun: The higher the sun is in the sky, the more light hitting your body is in the magic D zone of 290 - 300 nm. Beginning around 10 am the sunlight angle is enters into the magic zone. At noon is when Vitamin D production is highest as that is the time when most of the light hitting your body is in the magic zone of ~300 nm. As such, 15 - 20 minutes of full sun at noon WTIH NO SUNSCREEN ON will produce all the Vitamin D you likely need with the least amount of skin cancer risk.

Here are excerpts from two studies on this subject I found very interesting. If this subject fascinates you I HIGHLY recommend the second study I link below, full of super interesting information and not dry at all.

https://pubmed.ncbi.nlm.nih.gov/18348449/

To get an optimal vitamin D supplement from the sun at a minimal risk of getting cutaneous malignant melanoma (CMM), the best time of sun exposure is noon.

The reasons for this are (1) The action spectrum for CMM is likely to be centered at longer wavelengths (UVA, ultraviolet A, 320-400 nm) than that of vitamin D generation (UVB, ultraviolet B, 280-320 nm).

(2) Scattering of solar radiation on clear days is caused by small scattering elements, Rayleigh dominated and increases with decreasing wavelengths. A larger fraction of UVA than of UVB comes directly and unscattered from the sun.

(3) The human body can be more realistically represented by a vertical cylinder than by a horizontal, planar surface, as done in almost all calculations in the literature. With the cylinder model, high UVA fluence rates last about twice as long after noon as high UVB fluence rates do.

In view of this, short, nonerythemogenic exposures around noon should be recommended rather than longer nonerythemogenic exposures in the afternoon. This would give a maximal yield of vitamin D at a minimal CMM risk

Each of the following paragraphs are snippets from the larger study I link below

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3897598/

People who live farther North and South often cannot make any vitamin D3 in their skin for up to 6 mo of the year.41 For example in Boston at 42° North essentially no vitamin D3 can be produced in the skin from November through February. Inhabitants living in Edmonton Canada at 52° North, Bergen Norway at 60° North, or Ushuaia Argentina at 55° South are unable to produce any significant vitamin D3 for about 6 mo of the year (Figs. 23 and ​and2424).2,39,41

In the early morning and late afternoon the zenith angle of the sun is also more oblique similar to winter sunlight and as a result very little if any vitamin D3 can be produced in the skin before 10 a.m. and after 3 p.m. even in the summer time (Figs. 23 and ​and2525).44

Since glass absorbs all UVB radiation, exposure of the skin to sunlight that passes through glass, plexiglass, and plastic will not result in any production of vitamin D3 in the skin (Fig. 29).31\

Sunscreens were designed to absorb solar UVB radiation.47 A sunscreen with a sun protection factor (SPF) of 30 absorbs approximately 95–98% of solar UVB radiation. Therefore the topical application of a sunscreen with an SPF of 30 reduces the capacity of the skin to produce vitamin D3 by the same amount i.e., 95–98%.22 This was confirmed with the report that the application of sunscreen with a SPF of only 8 dramatically reduced the blood level of vitamin D3 after exposure to simulated sunlight in a tanning bed (Fig. 30).47,48