Environment lighting

Simulate light from the surroundings of your scene, for example the sky or a lighting studio, in the High Definition Render Pipeline (HDRP).

HDRP does the following to create environment lighting:

Renders a background, for example an HDRI sky texture or a gradient. For more information, refer to Sky.
Uses the sky to calculate how the GameObjects in your scene receive indirect ambient light. To control the light, use the Environment (HDRP) tab of the Lighting window.

How HDRP calculates ambient light

Depending on your settings and baked lighting, HDRP fetches the sky color for a GameObject from one of the following:

The default ambient light probe, which captures either the static sky in the Environment (HDRP) tab of the Lighting window, or the dynamic sky at runtime from the Visual Environment volume override.
Baked lightmap textures from lightmapping.
Realtime lightmap textures from Enlighten Realtime Global Illumination.
Adaptive Probe Volumes.
Screen space global illumination or ray-traced global illumination.

Note: HDRP calculates the ambient Light Probe on the GPU, then uses asynchronous readback on the CPU, so the lighting is one frame late.