types of clouds and how high they are
Clouds come in ten main types, sorted into three levels by how high they usually form. In mid-latitudes, high clouds sit about 5 to 13 km up (16,500 to 45,000 ft), middle clouds 2 to 7 km (6,500 to 23,000 ft), and low clouds from the ground to 2 km (6,500 ft). The levels overlap, and they sit higher in the tropics and lower near the poles.
The ten types of clouds
The World Meteorological Organization's International Cloud Atlas names ten cloud genera and gives each level a range of heights where those clouds occur most often.
| cloud | level | mid-latitudes | tropics |
|---|---|---|---|
| Cirrus | high | 5–13 km | 6–18 km |
| Cirrocumulus | high | 5–13 km | 6–18 km |
| Cirrostratus | high | 5–13 km | 6–18 km |
| Altocumulus | middle | 2–7 km | 2–8 km |
| Altostratus | middle | 2–7 km | 2–8 km |
| Nimbostratus | middle | 2–7 km | 2–8 km |
| Stratocumulus | low | 0–2 km | 0–2 km |
| Stratus | low | 0–2 km | 0–2 km |
| Cumulus | low | 0–2 km | 0–2 km |
| Cumulonimbus | low | 0–2 km | 0–2 km |
How high are clouds?
Usually between the ground and about 13 km in mid-latitudes. By level:
- High clouds: 5 to 13 km, or 16,500 to 45,000 ft (3.1 to 8.1 miles). In the tropics 6 to 18 km; near the poles 3 to 8 km.
- Middle clouds: 2 to 7 km, or 6,500 to 23,000 ft (1.2 to 4.3 miles). In the tropics up to 8 km.
- Low clouds: from the surface to 2 km, or up to 6,500 ft (1.2 miles), everywhere.
Some clouds do not stay in their level. Altostratus often reaches higher, nimbostratus usually spreads into the levels above and below, and cumulus and cumulonimbus have their bases low while their tops may reach the middle and high levels.
Cumulonimbus vs cumulus
Cumulus are separate heaps: dense, with sharp outlines, growing upward into mounds whose bulging tops look like a cauliflower. Where the sun hits them they are bright white, and their base is darker and nearly flat.
Cumulonimbus is much bigger: a heavy, dense cloud of great height, built like a mountain or a huge tower. Its top is nearly always flattened and often spreads out like an anvil, and its base is often very dark. So a bulging cauliflower top usually means cumulus, and a flattened top spreading like an anvil usually means cumulonimbus.
Look up on your walk
Knowing a cloud's name gives you one more reason to look up. People who looked out for vast things on their walks reported more joy, and why a walk clears your head has the study behind that.
Where Angel Step fits
Angel Step puts today's steps on your Home Screen and Lock Screen over a sky whose clouds open as you walk. It does not forecast or identify clouds.
Sources
- World Meteorological Organization, International Cloud Atlas — levels and their heights by latitude. WMO
- WMO, International Cloud Atlas — definition of cumulus. WMO
- WMO, International Cloud Atlas — definition of cumulonimbus. WMO
- Hong Kong Observatory — the classification and nomenclature of clouds. Hong Kong Observatory
Updated