What the map shows
Where low, middle and high clouds each sit, so you can tell a thin high-cloud shield from a solid overcast.
How to read the colors
Gray shading shows low clouds, purple shows middle clouds, and blue shows high clouds. Read each layer's percentage scale separately; overlapping layers blend together.
Common mistakes
- Assuming high thin cloud will block the sun as much as low thick cloud.
- Adding the three layers together and expecting 100% overcast — the layers overlap.