Clouds Explained
Estimated Lesson Time: 35–45 Minutes
Lesson Overview
In previous lessons, we’ve explored Display Settings, Anti-Aliasing, Frame Generation, Render Scaling, Terrain Level of Detail, Object Level of Detail, Texture Resolution and Texture Filtering.
Today we’re going to explore one of the most visually impressive features in Microsoft Flight Simulator:
Volumetric Clouds.
Unlike older flight simulators that used flat cloud textures, Microsoft Flight Simulator creates fully three-dimensional clouds that interact with light, weather and the environment.
These clouds are one of the biggest reasons the simulator looks so realistic.
However…
They are also one of the most demanding graphics features.
Understanding Cloud Quality will help you balance visual realism with GPU performance.
Lesson Objectives
By the end of this lesson you will understand:
What volumetric clouds are.
How the weather engine creates clouds.
Why clouds are GPU intensive.
How Cloud Quality affects image quality.
How clouds influence FPS.
When to increase or decrease Cloud Quality.
How to choose the best setting for your graphics card.
1. What Are Volumetric Clouds?
Traditional flight simulators often displayed clouds using flat two-dimensional images, sometimes called “billboards.”
These clouds looked convincing from certain angles but could appear unrealistic as you flew around them.
Microsoft Flight Simulator uses volumetric clouds.
Volumetric means the clouds have real three-dimensional volume.
You can:
Fly around them.
Fly through them.
See sunlight pass through them.
Watch shadows move across them.
Observe different cloud layers interacting.
This creates a much more realistic atmosphere.
Think Of It Like Cotton Wool
Imagine two clouds.
The first is simply a photograph stuck on a wall.
The second is an actual ball of cotton wool floating in the air.
The cotton wool has depth.
Light passes through it.
It casts shadows.
It changes depending on where you’re standing.
That’s essentially the difference between flat cloud textures and volumetric clouds.
2. How The Weather Engine Works
Microsoft Flight Simulator has a sophisticated weather engine.
It calculates:
Cloud layers.
Humidity.
Atmospheric pressure.
Temperature.
Wind.
Visibility.
Storm systems.
Rain.
Snow.
Fog.
Live weather (if enabled) or selected weather presets are used to generate these atmospheric conditions.
The weather engine determines where clouds should exist, while the GPU renders their appearance.
Weather Engine vs GPU
It’s useful to separate these two jobs.
The weather engine decides:
- What weather exists.
- Where cloud layers are.
- Their altitude.
- Their density.
The GPU then draws those clouds on screen using volumetric rendering.
This means cloud quality mainly affects the graphics workload rather than the weather simulation itself.
3. Why Clouds Are So Demanding
Clouds are one of the most GPU-intensive features in Microsoft Flight Simulator.
Unlike a building, which stays in one place, clouds are constantly interacting with:
Sunlight.
Shadows.
Atmospheric lighting.
Weather effects.
Fog.
Rain.
Each cloud contains thousands of tiny volume samples that must be processed.
The GPU calculates:
Light scattering.
Cloud density.
Transparency.
Cloud edges.
Shadowing.
Reflections of light.
This has to happen every frame.
Why GPU Load Increases
Imagine rendering a clear blue sky.
Very little work is required.
Now imagine rendering:
- Thunderstorms.
- Thick overcast.
- Towering cumulus clouds.
- Multiple cloud layers at sunset.
The GPU has to calculate far more information.
This is why FPS often drops in heavy weather.
4. Cloud Quality
Microsoft Flight Simulator usually provides several Cloud Quality options.
Examples include:
- Low
- Medium
- High
- Ultra
Each level changes how detailed the clouds appear.
Low
Lowest GPU workload.
Simple cloud shapes.
Less realistic lighting.
Reduced cloud depth.
Suitable for entry-level hardware.
Medium
Improved cloud structure.
Better lighting.
Moderate GPU demand.
Good compromise.
High
Excellent cloud detail.
Natural lighting.
Well-defined cloud edges.
Suitable for many modern systems.
Ultra
Maximum cloud detail.
Outstanding lighting.
Highly realistic cloud formations.
Best cloud shadows.
Most demanding on the GPU.
5. GPU Load
Cloud Quality is primarily a GPU setting.
Increasing Cloud Quality increases:
GPU utilisation.
GPU temperature.
GPU power consumption.
VRAM usage (to a lesser extent than Texture Resolution).
Unlike Terrain LOD…
Cloud Quality has relatively little direct impact on CPU performance.
If your simulator is GPU limited, Cloud Quality is one of the first settings worth evaluating.
6. Flying Through Clouds
One of the biggest differences between Low and Ultra appears when flying inside cloud layers.
Higher settings provide:
Smoother cloud edges.
Better depth perception.
More realistic lighting.
Improved visibility transitions.
At lower settings:
Clouds may appear simpler.
Lighting transitions can be less natural.
Cloud interiors may feel less immersive.
7. Cloud Shadows
Clouds don’t only affect the sky.
They also cast shadows across:
Mountains.
Cities.
Fields.
Runways.
Water.
These moving shadows add realism to the environment.
Higher Cloud Quality generally produces more detailed and natural-looking cloud shadows.
8. Weather Conditions
Not every flight places the same demand on your GPU.
Clear Skies
Lower GPU workload.
Higher FPS.
Broken Clouds
Moderate GPU workload.
Heavy Overcast
High GPU workload.
Thunderstorms
Very high GPU workload.
Large cloud volumes.
Heavy lighting calculations.
Expect lower FPS.
9. Live Weather
When Live Weather is enabled, cloud conditions change according to real-world meteorological data.
Some days you may experience:
Bright sunshine.
Other days:
Heavy storms.
This means performance may naturally vary between flights, even with identical graphics settings.
Always keep weather conditions in mind when comparing benchmarks.
10. When Should You Increase Cloud Quality?
Increase Cloud Quality if:
- Your GPU has spare performance.
- You enjoy realistic weather.
- You fly IFR through cloud layers.
- You enjoy sunrise and sunset flights.
- You value visual immersion.
11. When Should You Reduce Cloud Quality?
Reduce Cloud Quality if:
- Your GPU is consistently near full utilisation.
- Heavy weather significantly reduces FPS.
- You fly at 4K on a mid-range GPU.
- You need additional performance but wish to keep other visual settings high.
Cloud Quality is often one of the most effective GPU settings to adjust.
12. Common Myths
Myth 1
“Clouds mainly affect the CPU.”
False.
Cloud Quality is primarily GPU intensive.
Myth 2
“Ultra Clouds always destroy FPS.”
Not necessarily.
The impact depends on:
Resolution.
Weather conditions.
GPU performance.
Other graphics settings.
Myth 3
“Clear weather and thunderstorms perform the same.”
False.
Cloud density has a significant effect on GPU workload.
Student Exercise
Today we’re going to compare Cloud Quality settings.
Step 1
Load your Module 1 benchmark flight.
Use:
- Same airport.
- Same aircraft.
- Same resolution.
Select a weather preset with significant cloud cover to make the comparison meaningful.
Step 2
Test:
Cloud Quality:
- Medium
- High
- Ultra
Step 3
During each test, record:
- Average FPS.
- Lowest FPS.
- GPU utilisation.
- GPU temperature.
- Cloud realism.
- Lighting quality.
- Cloud shadows.
- Overall smoothness.
Step 4
Compare the results.
Ask yourself:
- Which setting looked most realistic?
- How much GPU performance did each level require?
- Was the visual improvement worth the FPS cost?
- Which setting provides the best balance for your system?
Student Checklist
Cloud Quality tested.
GPU utilisation monitored.
GPU temperature recorded.
Cloud realism compared.
Cloud shadows evaluated.
Best Cloud Quality selected.
Lesson Summary
Congratulations.
You now understand one of the most visually impressive settings in Microsoft Flight Simulator.
Remember:
- Volumetric clouds are fully three-dimensional and contribute greatly to the simulator’s realism.
- The weather engine determines cloud conditions, while the GPU renders them.
- Cloud Quality is primarily a GPU-intensive setting.
- Higher Cloud Quality improves cloud detail, lighting and shadows but increases GPU workload.
- Performance can vary depending on weather conditions, even if your graphics settings remain unchanged.
- There is no universal “best” Cloud Quality setting—choose the level that delivers the right balance between realism and performance for your hardware.
Knowledge Check
- What are volumetric clouds?
- What is the difference between the weather engine and the GPU when rendering clouds?
- Why are clouds one of the most demanding graphics features in Microsoft Flight Simulator?
- Which hardware component is primarily affected by Cloud Quality?
- How do weather conditions influence cloud performance?
- When should you consider reducing Cloud Quality?
- Why is it important to benchmark using similar weather conditions?
- Based on your testing, which Cloud Quality setting provides the best balance between visual realism and smooth performance on your PC?