Question 1 of 15
How many cloud genera does the WMO International Cloud Atlas recognize?
Why: The ten genera: cirrus, cirrocumulus, cirrostratus, altocumulus, altostratus, nimbostratus, stratocumulus, stratus, cumulus, cumulonimbus.
Question 2 of 15
What does the species name 'castellanus' describe?
Why: Castellanus turrets signal instability aloft — altocumulus castellanus in the morning often means thunderstorms by afternoon.
Question 3 of 15
Which cloud species means 'hair-like'?
Why: Capillatus (Latin for 'having hair') describes cumulonimbus with a fibrous, striated upper portion — a mature thunderstorm.
Question 4 of 15
What is 'cumulonimbus incus'?
Why: Incus is Latin for 'anvil' — the flat spreading top of a mature storm at the tropopause.
Question 5 of 15
The rare 'asperitas' cloud feature was officially added to the WMO Cloud Atlas in what year?
Why: Asperitas — chaotic, wave-like undersides — became the first new cloud classification in over half a century in the 2017 Atlas.
Question 6 of 15
What supplementary feature name describes a 'wall cloud'?
Why: Murus (Latin for 'wall') was added to the 2017 Atlas for the lowered, often rotating cloud base under a supercell.
Question 7 of 15
What is a 'tuba'?
Why: Tuba is the official term for a condensation funnel that doesn't reach the ground — a funnel cloud.
Question 8 of 15
'Cauda' — another 2017 addition — describes what?
Why: Cauda is the tail cloud extending horizontally from a wall cloud toward the precipitation core.
Question 9 of 15
What variety name describes clouds arranged in parallel rows?
Why: Radiatus rows appear to converge toward the horizon like railroad tracks — common in cumulus streets.
Question 10 of 15
What is 'pileus'?
Why: Pileus forms when a strong updraft pushes moist air up and over the growing tower — it often signals a storm about to strengthen.
Question 11 of 15
Which cloud genus NEVER produces precipitation that reaches the ground?
Why: Cirrus is composed of ice crystals that sublimate long before reaching the surface (fall streaks/virga at best).
Question 12 of 15
What is the typical base height of nimbostratus?
Why: Nimbostratus is the low, thick, gray blanket that brings steady rain or snow.
Question 13 of 15
'Kelvin-Helmholtz' wave clouds form because of what?
Why: When a fast layer slides over a slow one, breaking-wave curls form at the boundary — the same instability seen in ocean waves.
Question 14 of 15
What does 'fractus' mean in cloud names like cumulus fractus?
Why: Fractus clouds are ragged shreds — common under storm bases (scud) or during rapidly changing weather.
Question 15 of 15
Which of these is a 'homogenitus' cloud?
Why: Homogenitus means human-made — contrails and power-plant cumulus earned an official suffix in the 2017 Atlas.