**System Information (1):**
Operating system: Linux-5.4.0-7634-generic-x86_64-with-debian-bullseye 64 Bits
CPU: Ryzen 9 3900X
Graphics card: Nvidia GTX 1050Ti 440.82
**System Information (2):**
Operating system: Windows-10-10.0.19041
CPU: Ryzen 9 3900X
Graphics card: Nvidia GTX 1050Ti 440.82
**Blender Version:**
Broken: 2.90.0 `rBb89898cbd381` (2020-06-18 19:05)
Worked: N/A as this feature was introduced in 2.90.0 a few days ago.
**Short description of error:**
When the sun elevation of the Nishita sky texture is set between -.0007 and 0 degrees, there are some artifacts. Here is an animation showing the artifacts as the sun progresses from the elevation -0.001 to 0 degrees. This issue occurs when rendering with the CPU, CUDA, and OptiX. Haven't tested OpenCL.
{F8631795}
**Exact steps for others to reproduce the error:**
1. Create a new scene and select `Cycles` as your render engine.
2. In a shader editor for the world material, add a `Sky texture` node and connect it to the `Background` node that should already be there.
3. Setup the sky texture node to use the Nitisha model with the settings shown in the screenshot below.
3. Change the sun elevation to something between -0.0007 and 0 degrees and notice the artifacts near the sun disk. These artifacts get worse the closer the value is to 0 degrees.
{F8631810}
Here is a .blend file where I have animated the sun elevation between -0.001 and 0 degrees between frames 1 and 120. Scroll through the time line to see the artifacts. {F8631813}