Hi 3DArtist, here an amazing free HDRi resource from HDRMAPS aka artist Grzegorz Wronkowski, has released a free HDRi Sky timelapse, unclipped 300 hdri frames, shot every 5 seconds with 10 stops ND filter. Each frame is almost 10K resolution, get it for free now.
Free high-resolution timelapse HDRI sky animated, to download!
Free HDRI sky video timelapse
This package is around 17GB of filesize, please download it only when really needed, downloading such a huge package can take around 30 minutes or more. Please use direct download link from Mediafire below (no log in required):