Physical Atmosphere² 2.7.4 for Blender

For those who don’t know the tool: Physical Atmosphere is a Blender 5.2 extension from Physical Addons that creates the scene’s sky, celestial bodies, volumetric clouds and World lighting for Eevee and Cycles. It sits in environment look development and lighting, can derive cloud coverage from NOAA’s Global Forecast System, and is distributed through Superhiv.

More than a redesigned panel

Physical Atmosphere² succeeds Physical Starlight and Atmosphere, but its central changes are renderer and simulation changes rather than a new interface placed over the previous system. The developer now has a spherical planet, wavelength-aware atmospheric rendering, multiple scattering, atmospheric refraction, airglow, ozone modelling, aerosol profiles based on OPAC, planetary ground shading and sky continuity from ground level to orbital views. Those capabilities alter the generated light and image, not just additional sliders.

The interface then exposes that system through Simple, Advanced and Scientific layouts. Simple consolidates location, time, clouds, exposure and quality on one screen. Advanced exposes the working physics, cloud layers and rendering controls. Scientific makes the complete parameter set available, although the developer promises its dedicated technical documentation will follow later. Tthe layouts are interfaces to the same underlying system, not separate rendering algorithms or quality tiers. A Scientific tab does not, by itself, constitute scientific validation, just as a large node graph does not automatically constitute compositing. And no, Keith, just because it’s a 30K resolution does not make it a good image.

The add-on owns the World

Physical Atmosphere² ships as a Blender extension ZIP. It can be dragged into Blender or installed through Get Extensions using Install from Disk. Adding the atmosphere creates and manages its own World for the active scene, together with the sky and sunlight required by the system. Removing the atmosphere removes that setup again. This makes first use direct, but it also means studios with established World nodes, environment-lighting templates or pipeline scripts must check how those assets interact with the managed World before adopting it across a show.

Color management also needs attention. The experimental Blend Objects into Atmosphere mode was designed to apply atmospheric haze and the add-on’s own tonemapping to scene geometry. It is currently disabled while its compositor is adapted to the 2.6.0 sky pipeline. With the option disabled, Blender’s regular View Transform and Look controls apply. That is a material limitation for shots requiring integrated aerial perspective on foreground geometry, not just a temporarily greyed-out convenience button.

Physics with an artistic exit

Earth mode accepts a real location, date, time, altitude, time zone and daylight-saving setting, then calculates the sun, moon and visible planets. Artistic mode replaces the calendar with direct placement controls. Artists can therefore begin from astronomical conditions and depart from them when composition wins the argument, as it frequently does shortly before final delivery. Camera controls include exposure in EV or photographic aperture, shutter speed and ISO, plus white balance and a separate World Output control for changing scene illumination without changing the visible sky.

Atmospheric controls cover Rayleigh scattering, aerosols and turbidity, OPAC aerosol profiles, ozone, airglow, atmospheric refraction and multiple scattering. An optional Hillaire LUT provides an alternative method for multiple scattering. This is a genuine algorithm choice exposed to the artist, whereas its multiplier is an art-direction control applied to the chosen method. The sun can use a measured AM0 spectrum or a blackbody model, with an adjustable number of spectral samples.

OPAC itself provides optical properties for representative aerosols and clouds across solar and terrestrial wavelengths. Using those profiles gives the renderer more meaningful starting conditions than labelling a generic density slider “punchy”. However, Physical Addons’ public documentation does not currently provide the full equations, default spectral sampling values, numerical error bounds or a calibration report against measured reference imagery.

Clouds from controls or forecasts

The cloud renderer supplies three volumetric layers, L0, L1 and L2, plus a rain layer. Every layer can receive global and local coverage maps, including custom images, and exposes altitude, thickness, density, large-scale shape, fine detail, droplet size, wind phase and silhouette controls. Shared controls add wind flow, anti-tiling, turbulence and separate speeds for shape and detail evolution. Cloud Time Scale can stop the system at zero or run it backwards with negative values, which is useful when a carefully approved weather cue has drifted three frames past the edit.

Cloud shading offers KSA, Hybrid and Octave MS models. KSA is the default reference look, Hybrid exposes the extensive Physical Starlight and Atmosphere-style controls, and Octave MS provides another energy-conserving treatment. Artists can adjust Mie scattering strength, droplet behaviour, direct and indirect anisotropy, backscatter, shadow depth, multiple-scattering gain, inner glow, out-scattering and ambient occlusion. These are artist-facing controls rather than a published cloud-rendering API. The developer says the lighting was compared with Cycles path tracing, and the release includes tools to isolate components or bake the procedural clouds into OpenVDB for side-by-side rendering.

The weather workflow downloads the forecast nearest the scene’s date and time from the Global Forecast System, generates coverage maps and stores them beside the project or in a chosen folder. Network permission is used for GFS data and automatic location detection; file permission is used to save the maps. The rest of the add-on can operate offline. NOAA describes GFS as a global model producing atmospheric and land variables four times daily, but the add-on documentation does not specify its exact endpoint, available forecast horizon, interpolation method or fallback behaviour when the requested time is unavailable.

For reproducible work, generated weather maps should be archived with the shot rather than regenerated whenever a file is opened. A live forecast is an input source, not immutable production media. OpenVDB baking likewise provides a useful validation and interchange route, but its presence does not certify the result in Houdini, Maya or another volume-capable DCC.

https://superhivemarket.com/products/physical-atmosphere

https://www.physicaladdons.com/physical-atmosphere/documentation/
https://www.physicaladdons.com/physical-atmosphere/release-notes/