Disclaimer
This description was translated from French using ChatGPT.

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🌤️ Project Atmosphere

Dynamic Climate & Weather Simulation for Forge 1.20.1 / NeoForge 1.21.1
(Active Development — Core Beta Series)

Join the Discord Server to post suggestions, report bugs, and access experimental builds.

Project Atmosphere is a Minecraft mod that replaces random cloud spawning from Simple Clouds with a highly realistic and fully dynamic atmospheric system.

Instead of relying on chance, clouds, weather, and visual effects emerge from a real climate simulation. Project Atmosphere introduces temperature, pressure, humidity, and wind systems inspired directly by real world meteorology.

The same principles and equations used by weather forecasters are applied here to simulate how the atmosphere behaves over time. Every biome evolves according to physical rules, not random events.

The result is a living atmosphere where clouds form, move, grow, or dissipate naturally based on environmental conditions. Weather becomes a consequence of atmospheric balance rather than a scripted event.

⚙️ How This Works

Project Atmosphere starts by generating a 7 day forecast that acts as the initial atmospheric foundation.

Once this forecast exists, the system analyzes it to locate low pressure areas, which usually form around two to three dominant cyclonic zones. When such an area is detected, a cyclone or low pressure zone is created.

This zone becomes an attractor. Pressure, humidity, and wind values gradually evolve toward it, exactly like in real atmospheric systems. Because of this interaction, once the initial forecast is generated, the mod does not need to constantly regenerate new forecasts. The atmosphere naturally evolves on its own.

Temperature Evolution

Temperature is driven by sunlight exposure.

For each biome, Project Atmosphere calculates the maximum temperature it could theoretically reach if it were exposed to sunlight for the entire day. Then, using cloud coverage data, the system determines how many hours of sunlight actually reached the ground.

The difference between full exposure and real exposure directly defines the temperature evolution throughout the day.

Biome and Regional Logic

Each biome has its own temperature profile, but this is only used during the initial forecast generation.

After the forecast is created, Project Atmosphere switches to a single regional forecast that covers an area with a radius of roughly 1000 blocks.

This regional approach is significantly simpler, more stable, and much lighter to simulate, while still producing coherent and believable climate behavior across biomes.

Performance First Design

On top of being realistic, Project Atmosphere is built with performance as a priority. As someone who really dislikes poorly optimized games, all heavy computations are fully offloaded to asynchronous threads.

To make this possible, Project Atmosphere uses a custom clone of the biome sampler. If you are familiar with seed map websites used to visualize Minecraft worlds, this system works in a very similar way.

By relying on this cloned biome map, the mod can safely access biome and climate data without interacting directly with live world chunks. This prevents concurrency issues and allows all atmospheric calculations to run asynchronously without impacting gameplay performance.

☁️ Cloud Formation and Types

Project Atmosphere adds 40+ new cloud types. Each cloud is classified on a 1 to 7 scale, where 1 represents an almost clear sky and 7 represents extreme systems like hurricanes. Hurricanes are planned, but not fully ready yet.

Cloud intensity is determined by combining humidity, pressure, and additional atmospheric factors to produce a value from 1 to 7. This value is then multiplied by a configurable factor from the mod’s config.

On top of that, Project Atmosphere tracks recent severe cloud activity. The longer it has been since a cloud above level 5 formed, the more an additional scaling value grows, increasing the likelihood and strength of major formations over time.

Some cloud types are realistic and meteorology inspired, while others are intentionally fictional to expand variety and visuals.

🌪️ Tornadoes and Hurricanes

Tornadoes are currently available through commands and configuration options, but they are still a work in progress. Visually, they are not great yet, because shader work takes time and this is still actively improving.

Tornadoes can also be performance heavy, so a config option is included to let you toggle them on or off. Once the mod is more stable, tornado visuals and performance will be revisited and improved.

Hurricanes are also not fully implemented yet. Simple Clouds was not designed to support massive storm structures with a true hollow eye, so Project Atmosphere currently represents hurricanes using a custom cloud type called custom_cumulonimbus.

For now, treat hurricanes as a huge tropical storm system rather than a final hurricane implementation.

🔌 Integrations

As a Minecraft player myself, I really value mods that interact well with others. Project Atmosphere was designed from the start with mod integration as a core goal.

Temperature Mod Integrations

Project Atmosphere previously integrated directly with several temperature based survival mods:

Legendary Survival Overhaul
Cold Sweat
Tough As Nails

These integrations existed when temperature was handled per biome. Since the system now uses a regional forecast, these integrations may evolve.

One possible future direction is linking weather conditions instead of raw temperature values, for example lowering perceived temperature during rain or storms.

Biome and Climate Mapping

The forecast system relies on configured normal temperature ranges per biome to evaluate whether generated values are realistic.

Project Atmosphere includes mappings for many popular biome mods:

Biomes O Plenty
Still Life
Atmospheric
TerraFirmaCraft
Terralith
Nature’s Spirit
Regions Unexplored
Biomes We’ve Gone
Galosphere
Neapolitan
Integrated Dynamics
Autumnity

TerraFirmaCraft Compatibility

TerraFirmaCraft is supported.

The integration is still being improved, but it already allows you to play Project Atmosphere alongside TFC in a functional way.

TFC compatibility build

Weather and Visual Integrations

Desert Storms
Adds sandstorms driven by atmospheric conditions
Continent and Tectonic
These mods create larger oceans, which significantly improve forecast accuracy
Rainbows and Auroras
Functional but still under development
Pretty Rain
Automatically integrated through Simple Clouds

Required Mods

Project Atmosphere requires a season system to function. One of the following is mandatory:

TerraFirmaCraft
Ecliptic Seasons
Serene Seasons

Additional required mods:

Gabou’s Libs
Simple Clouds

Recommended Mods for the Best Experience

Serene Seasons
Serene Seasons Plus
Tectonic or Continent

⚡ Performance Guidelines

Optimized for RTX class GPUs and modern CPUs
Tested on:
GPU: RTX 4070 Ti SUPER (main), RTX 2060 (low end)
CPU: Intel 13700K @ 5.4GHz (main), Ryzen 5 3600X (low end)
Heavy use of floating point simulation and SSBO rendering. Older hardware may experience slowdowns.

⚠️ Disclaimer

Project Atmosphere is in active beta. Forecast data formats and configuration options may change between versions. Always back up your worlds before updating.

Atmospheric Shaders Compatibility

You can use Atmospheric Shaders made for Simple Clouds alongside Project Atmosphere.

Project Atmosphere: Realistic Climate & Weather