Why does light diffraction create circular patterns?

[abrahamabraham]

TL;DR Summary

We see under trees circular light that goes from sun through the leaves gaps. Why does it create a circular shape and not other shapes? why does this diffraction phenomenon create it in circular patterns?

We see under trees circular light that goes from sun through the leaves gaps. Why does it create a circular shape and not other shapes? why does this diffraction phenomenon create it in circular patterns?

 

[berkeman]

Can you upload a couple pictures of what you are seeing? Use the "Attach files" link below the Edit window to upload a PDF or JPEG image.

The diffraction pattern will depend on the size and shape of the aperture. See the Wikipedia article for a good introduction to diffraction:

https://en.wikipedia.org/wiki/Diffraction

 

[.Scott]

In daylight conditions, sunlight passing through gaps in the leaf cover will not produce readily visible diffraction patterns.
But those gaps will act as pin-hole "lens"s. So in the shadow of the canape you will see projected images of the solar disk - which is circular.

 

[hutchphd]

But those gaps will act as pin-hole "lens"s.

I can attest to this because during an eclipse the circles turn into crescents. You are seeing a projected image of the face of the sun. There is an eclipse here on 8 april ......I will report

 

[.Scott]

I was living in Virginia during the 1984 annular eclipse. Hence ring-shaped shadows. Although we had clear skies, atmospheric effects combined with the annular shape to create some really weird lighting effects.

 

[Stadz]

In daylight conditions, sunlight passing through gaps in the leaf cover will not produce readily visible diffraction patterns.
But those gaps will act as pin-hole "lens"s. So in the shadow of the canape you will see projected images of the solar disk - which is circular.

Yes, this is exactly what I observe. Also, the size of the image varies with the distance from the aperture. Is there a formula for calculating the the size of the expected image for a given distance?