Helpful Cloud-Classification Characteristics
| Cloud Type | To Distinguish | Characteristic | Applications |
| Stratus |
Height (correlated with thickness) |
Shadow | Distinct shadows: Cirrostratus (thin) |
| "Watery" sun or moon: Altostratus (thicker) | |||
| No shadow or visible sun or moon: Stratus (thickest) | |||
| Cumulus | Height | Cloud-edge sharpness | Diffuse edge: Cirrocumulus |
| Sharp edge: Altocumulus or stratocumulus | |||
| Angular size (compare cloud element with hand held at arm's length) | "Pinky" nail-sized: Cirrocumulus | ||
| Thumb nail-sized: Altocumulus | |||
| Fist-sized: Stratocumulus or cumulus humilis |