Question 1 of 15
Where do noctilucent clouds form?
Why: Noctilucent ('night-shining') clouds are the highest clouds on Earth, glowing electric blue after sunset at high latitudes.
Question 2 of 15
Nacreous (mother-of-pearl) clouds form in what layer?
Why: Polar stratospheric clouds form at -108°F in polar winters — beautiful, but they also help destroy ozone.
Question 3 of 15
The famous 'Morning Glory' roll cloud regularly appears where?
Why: Every spring, glider pilots travel to Burketown, Australia to soar the 600-mile-long Morning Glory roll cloud.
Question 4 of 15
Lenticular clouds are frequently mistaken for what?
Why: Their smooth lens shape, hovering stationary near mountains, has generated UFO reports for decades.
Question 5 of 15
A 'fallstreak hole' (hole-punch cloud) is usually triggered by what?
Why: Aircraft trigger freezing in supercooled droplets; ice crystals fall out, leaving a expanding circular hole.
Question 6 of 15
What is a 'cloud street'?
Why: Horizontal roll convection organizes cumulus into long parallel lines — glider pilots ride them for hundreds of miles.
Question 7 of 15
Undulatus asperitas looks most like what?
Why: Asperitas is that turbulent, underwater-waves look — first new cloud type recognized in 51 years (2017).
Question 8 of 15
What conditions produce 'steam devils'?
Why: Arctic outbreaks over the still-warm Great Lakes produce rotating steam columns — mini vortices of fog.
Question 9 of 15
The Catatumbo lightning phenomenon (storm clouds nearly every night) occurs over which lake?
Why: Lake Maracaibo sees lightning ~260 nights a year — the highest lightning density on Earth.
Question 10 of 15
A 'cap cloud' sits stationary on top of what?
Why: Moist air forced over a summit condenses into a smooth cap that appears anchored while wind blows through it.
Question 11 of 15
What are 'von Kármán vortex streets' in clouds?
Why: Tall islands like Guadalupe shred the airflow into elegant paired spirals visible from satellites.
Question 12 of 15
Pyrocumulonimbus clouds are generated by what?
Why: Extreme fires create their own thunderstorms — with lightning that can ignite new fires.
Question 13 of 15
An 'arcus' cloud is the umbrella term for what?
Why: Arcus covers both shelf clouds (attached) and roll clouds (detached) — low horizontal formations on storm outflow.
Question 14 of 15
Where would you most likely see 'diamond dust'?
Why: Diamond dust is ice crystals precipitating from a cloudless sky — creating brilliant halos and sun pillars.
Question 15 of 15
What is a 'sun pillar'?
Why: Plate-shaped ice crystals reflect sunlight into a vertical column — most common at sunrise/sunset in cold weather.