Cloud Atlas
Altostratus (As)
A mid-level grey/blue sheet: the sun looks like it’s behind frosted glass.
How to spot it
- Uniform sheet, grey or bluish
- Sun often visible but muted (no sharp shadows on the ground)
- Can show streaks/virga hanging below
What it can mean
- Often signals the approach of a warm front
- Can thicken into nimbostratus (steady precipitation)
- Light precipitation can occur if thick
Photography tips
- Use silhouettes for mood
- Expose for the sun area to keep gradient detail
- Watch for virga — it’s visually striking