Cloud Study
Cloud names work like building blocks. Learn five roots and most of the sky becomes readable.
The Five Core Roots
These five build the names of the ten main cloud genera.
| Root | Meaning | Picture it as |
|---|---|---|
| cirro- | high, icy, wispy | feathers or hair |
| alto- | middle level | patches halfway up |
| strato- | spread in a layer | a grey blanket |
| cumulo- | piled or puffy | cotton or cauliflower |
| nimbo- / nimbus | rain-bearing | dark rain cloud |
Extra Shape Words
These do not create new genera. They describe a cloud's species, variety or special feature.
| Word | Literal clue | What you see |
|---|---|---|
| fibratus | fibrous | long straight fibres |
| uncinus | hooked | wisps ending in hooks |
| castellanus | castle | little cloud turrets |
| floccus | tuft of wool | loose tufts |
| stratiformis | layer-shaped | a broad cloud sheet |
| lenticularis | lens-shaped | a smooth “UFO” lens |
| fractus | broken | ragged cloud fragments |
| humilis | humble, low | small fair-weather Cumulus |
| congestus | piled up | tall cauliflower Cumulus |
| calvus | bald | smooth young Cumulonimbus top |
| capillatus | hairy | fibrous, icy storm top |
| volutus | rolled | a long horizontal cloud roll |
Feature Words
| Word | Meaning in the sky |
|---|---|
| incus | anvil-shaped storm top |
| mamma | hanging pouches; commonly called mammatus |
| virga | rain or ice streaks that do not reach the ground |
| arcus | arched shelf or roll at a storm's front |
| tuba | a funnel hanging from the cloud base |
| cavum | a hole in a thin cloud layer |
| fluctus | breaking Kelvin–Helmholtz waves |
| asperitas | a rough, chaotic underside |
| murus | a wall cloud |
| cauda | a tail cloud |
| pileus | a small cap above a growing cloud |
| velum | a veil around a cloud tower |
Origin Endings
| Ending | Meaning | Example |
|---|---|---|
| -genitus | generated by something | flammagenitus: made by fire; homogenitus: made by human activity |
| -mutatus | changed by something | homomutatus: a human-made cloud that changed into a more natural-looking form |
Mix the Roots
| Name | Built from | What it looks like |
|---|---|---|
| Cirrus | cirro | thin high streaks |
| Cirrocumulus | cirro + cumulus | tiny high ripples, a “mackerel sky” |
| Cirrostratus | cirro + stratus | a thin high veil; may form a halo |
| Altocumulus | alto + cumulus | middle-level puffs or rolls |
| Altostratus | alto + stratus | a wide grey middle-level sheet |
| Stratus | strato | a low flat blanket; fog is its ground-level cousin |
| Stratocumulus | stratus + cumulus | a low lumpy blanket |
| Nimbostratus | nimbus + stratus | a thick layer with steady rain |
| Cumulus | cumulo | separate puffy clouds with flat bases |
| Cumulonimbus | cumulus + nimbus | a huge vertical storm cloud with rain and lightning |
Nimbus is not a separate modern WMO cloud genus. It is the rain clue inside Nimbostratus and Cumulonimbus.
Read the Sky Fast
HIGH cirro- Cirrus · Cirrocumulus · Cirrostratus
MIDDLE alto- Altocumulus · Altostratus
LOW strato- Stratus · Stratocumulus
PUFFY cumulo- Cumulus
TOWERING Cumulonimbus: low base, huge vertical growth
RAIN nimbo- Nimbostratus = thick layer with steady rain
Cumulonimbus = showers, thunder and lightning
Bonus Shapes
| Shape | Quick meaning |
|---|---|
| Lenticular | smooth lens or “UFO” cloud near mountains |
| Mammatus | hanging pouches under a cloud |
| Shelf cloud | long wedge at the front of a storm; strong wind may follow |
| Wall cloud | lowered cloud base under a severe storm; rotation is a warning sign |
| Funnel cloud | rotating funnel that has not reached the ground |
| Contrail | aircraft condensation trail |
| Pyrocumulus | cumulus created above intense fire |
| Mushroom cloud | hot air and debris rising after a large explosion or eruption; not a WMO cloud genus |
One-Line Memory Trick
Cirro is high, alto is middle, strato is flat, cumulo is puffy, and nimbo brings rain.
References
- WMO International Cloud Atlas, “Genera”
- WMO International Cloud Atlas, “Definitions of clouds”
- WMO International Cloud Atlas, “Cloud classification summary”
- WMO International Cloud Atlas, “Etymology of Latin names of clouds”
- WMO cloud-height diagram
Author: Ope Tags: #science Links: