50 Fun Facts About Cloud

Which amateur meteorologist proposed the Latin cloud-naming system in 1802?

He was a London chemical manufacturer by trade; Goethe was so taken with the scheme he wrote four cloud poems dedicated to him.

How many basic cloud genera does the modern international classification recognise?

They come from five physical forms sorted by altitude: sheets, heaps, rolls, towers and wisps.

What does the Latin word 'cumulus' mean?

Small flat-bottomed cumulus humilis clouds are the classic sign of fair weather.

The name of the high, wispy cirrus cloud comes from a Latin word meaning what?

Cirrus is made of ice crystals and produces halos and sun dogs when sunlight passes through the hexagonal crystals.

The prefix in 'stratus' clouds means what?

They form flat, uniform sheets and rarely manage more than drizzle or a little snow.

Which prefix marks a mid-level cloud, as in altostratus and altocumulus?

High-level versions take cirro-, while low clouds have no altitude prefix at all.

What is the towering thunderstorm cloud with a flat, anvil-shaped top called?

The anvil forms where rising air hits the inversion near the tropopause and spreads out.

Roughly how high do the tops of typical mature thunderstorm clouds reach?

Unusually tall ones top out around 20,000 metres, and their bases can sink to just 6 metres above the ground.

By definition, a very low stratus cloud at ground level is called fog when visibility drops below what?

If visibility stays at 1 km or more, it is called mist instead.

Which fishing grounds off Newfoundland are often called one of the foggiest places on Earth?

The foggiest places tend to lie above cold ocean currents; the least foggy parts of the US are the southwestern deserts.

Which clouds, forming near the top of the mesosphere at 80-85 km, are Earth's highest?

That is about ten times the altitude of ordinary high clouds; ice can only form there below about minus 120 °C.

Night-shining mesospheric clouds were first recorded in 1885, two years after which volcanic eruption?

Observers studying the eruption's strange sunsets were sure they would have noticed the clouds earlier had they existed.

Mammatus clouds, the pouches hanging under a storm cloud, take their name from the Latin word for what?

The lumpy underside forms as cold air sinks in pockets while warm air rises around it.

Which smooth, lens-shaped clouds that form downwind of mountains are regularly mistaken for UFOs?

They sit in standing waves on the leeward side of a mountain and stay put even in strong wind.

'Contrail' is short for what?

Water vapour in jet exhaust freezes in the cold high air; soot and sulphur particles give the droplets something to condense on.

Which chemical, discovered as a seeding agent by Bernard Vonnegut in 1946, is most used to make clouds rain?

Its crystal lattice closely matches ice; the crystallography later surfaced in his brother Kurt's novel Cat's Cradle.

Which General Electric scientist discovered the principle of cloud seeding in July 1946?

He was researching aircraft icing with a deep freeze full of test agents; dry ice did the trick.

Which city seeded clouds before the 2008 Olympic Games to keep the opening ceremony dry?

Rockets carrying silver iodide were fired to make clouds rain out before they reached the stadium.

The Cloud Appreciation Society was founded in 2005 by which British writer?

His book The Cloudspotter's Guide became a BBC documentary, Cloudspotting.

In what year was the International Cloud Atlas first published?

Its colour photographic plates were cutting-edge and expensive; the 2017 edition is online and added 12 new formations.

Which wave-like, 'underwater'-looking cloud was added to the International Cloud Atlas in 2017?

The same edition formally named roll clouds volutus and hole-punch clouds cavum.

The Morning Glory, a roll cloud up to 1,000 km long, is regularly seen from Burketown in which country?

Glider pilots travel to the Gulf of Carpentaria each spring to ride it.

What is a fallstreak hole, also called a hole-punch cloud?

Passing aircraft can trigger the freezing, and the ice falls out as a streak.

Nacreous clouds, named for their mother-of-pearl colours, form in which layer of the atmosphere?

They appear only in the extreme cold of the polar winter, at 15 to 25 km up.

The thick clouds of Venus are made mainly of what?

Jupiter and Saturn, by contrast, have outer decks of ammonia cloud over water clouds below.

What is the scientific study of clouds called?

It is a branch of cloud physics within meteorology; Aristotle covered clouds in his Meteorologica around 340 BC.

Which 423 BC Aristophanes comedy has Socrates call certain sky-dwellers the only gods?

It was first performed at the City Dionysia in 423 BC.

Tiny dust, salt or smoke particles on which vapour condenses into cloud droplets are called what?

Without them, air would need far higher supersaturation before droplets could form.

Clouds form when air is cooled to which temperature?

Adding moisture from a nearby source can also raise the dew point up to the air's temperature.

Per NASA, what is the net effect of low and mid-level clouds on Earth's temperature?

They reflect sunlight, outweighing the warming caused by thin high clouds trapping heat.

A 'flammagenitus' cloud is one created by what?

Volcanic versions have reached 57 km, and nuclear mushroom clouds have climbed to 67 km.

A rotating 'wall cloud' at the base of a supercell, which can spawn tornadoes, is formally named what?

Incus is the anvil top of a cumulonimbus, and cauda is a tail-like feature.

Iridescent clouds get their rainbow colours from which optical effect?

Individual tiny droplets or ice crystals scatter the light into bands of colour.

Which company's 1996 business plan helped popularise the phrase 'cloud computing'?

Its conclusion was prosaic: sell server hardware to internet service providers.

Which company released S3 storage and the EC2 compute cloud in 2006, launching modern cloud computing?

Its cloud arm held about 31% of the infrastructure market in early 2023, ahead of Microsoft Azure and Google Cloud.

In cloud computing, what does the 'S' in SaaS stand for?

NIST recognised three service models in 2011: infrastructure, platform and software as a service.

Chicago's mirrored sculpture Cloud Gate, nicknamed 'The Bean', is the work of which artist?

Built between 2004 and 2006 in Millennium Park; Kapoor disliked the nickname at first.

Roll clouds are formally known by which Latin species name, added to the Cloud Atlas in 2017?

They are relatively rare and shaped by wind shear.

On Mars, clouds of which substance have been detected near the poles?

Cirrus, cirrocumulus and even fog have all been observed there.

Which cloud type contains ice crystals whose interactions produce hail and lightning?

Snow and graupel form in the upper part of the storm; the collisions between them build electrical charge.

Around 340 BC, which Greek philosopher wrote Meteorologica, summing up ancient weather knowledge?

It rested on intuition and simple observation rather than experiment, and genuinely scientific cloud study had to wait until the early 1800s.

Ground-level condensation that still leaves visibility above the fog threshold is called what?

The dividing line is whether you can see roughly a kilometre; below that the same low stratus loses its Latin name entirely.

What is the name for rain or snow that evaporates before it ever reaches the ground?

Altocumulus produces it often, while low stratus sits too close to the ground for any of its precipitation to vanish on the way down.

The outermost cloud decks of Jupiter and Saturn are made of which substance?

Beneath that sits a haze layer of ammonium hydrosulfide and then an inner deck of water clouds, with thunderheads spotted near the Great Red Spot.

Clouds from factory plumes are classed as cumulus homogenitus. What does the Latin mean?

Aircraft contrails that spread into wispy sheets get the matching label cirrus homogenitus.

The anvil-shaped top of a big thunderstorm cloud carries which Latin feature name?

It spreads flat because the rising air slams into the tropopause, where the air stops getting colder with height.

Stratus cataractagenitus is a cloud generated by spray from what?

The name is Latin for 'cataract-made', one of several 'genitus' labels that record what created a cloud.

Breaking-wave clouds caused by wind shear are named for Lord Kelvin and which German physicist?

He first described the instability in 1868, and the cloud feature it produces is formally called fluctus.

Which French naturalist's 1802 cloud-naming scheme flopped for using informal French phrases?

He is far better remembered for his early theory of evolution; the rival Latin system proposed in England the same year won out instead.

What is the name for the smooth cap cloud that can form over the top of a rising cumulus?

Its sibling feature, the velum, is a thin horizontal sheet that forms like an apron around the middle of the parent cloud instead.