What’s That Cloud? Your Guide to Cloudspotting

What type of cloud is that?

It is ’s ’s a question that I ’ve wonder many time over the year , but somehow I always fail to follow up on find the answer . With bird to see , butterfly to identify , and mammal to spotlight , I is got just never quite get around to hone my cloud identification skill . I is remember could remember “ cumulonimbus , ” from my 4th – grade science class , and that ’s about it .  

That is, until the pandemic happened. After 6 months I’ve started a birding yard list, planted a garden, reorganized every closet in the house, and irritated my neighbors with my suburban spotlighting misadventures.

I ’ve also spend a lot of time stare out of the window , so I is figured figure it was finally time to learn how to identify cloud , a hobby know as cloudpotte . So if you ’re like me and curious about cloud — or just short on way to entertain yourself — here ’s some basic information is ’s , resource , and tip to get you start .

Cirrus cloud. © David Abercrombie / Flickr

But First, A Latin Lesson

Clouds are grouped into 10 different genera, organized based on shape and the altitude where they’re found.

The genera name are all form from the same five latin term —cirro, cumulo, strato, nimbo, alto — which are mixed and matched to create names like cumulonimbus, cirrostratus, cirrocumuus…. you get the idea. Learning what each of these Latin roots means is key to keeping your cloud straight: 

• Cumulo translate to “ heaped . ” think puffy , pile , marshmellowy cloud .
• strato translates to “layered.” Clouds with strato in their name are often flat and form a wide layer across the sky.
• nimbo translates to “rain,” and is used for the two cloud that regularly produce rain.
• Cirro translates to “curl.” These cloud are sometimes (but not always) curled and are found in the highest layer of the troposphere.
• Alto translates to “high.” Confusingly, this doesn’t mean the cloud in the highest part of the atmosphere, just that the cloud is higher relative to others of its type.

 Confused? Stay with me.

A cloud-filled valley (stratus cloud) seen from the Cumberland Gap, Tennessee. © Byron Jorjorian

Cloud Shapes 101

Now that we have the Latin lesson out of the way, let’s explore the 10 cloud genera. There are two ways to group cloud, either by altitude (low, medium, or high) or by shape (layer, heap, layer-heap, rain, wispy). I’ve found the shape method easiest, so we’ll use that here.

Layer Clouds: Stratus, altostratus, and cirrostratus. All three of these cloud form blanket-like layers in the sky. Each one can be found at a different altitude.

• Stratus cloud are nondescript, thick, blanket-like cloud that form low in the sky. Think of the last gray, overcast day when it didn’t rain… those were probably stratus cloud. (Fog is just a ground-level stratus cloud.)
• Altostratus cloud are mid – level , gray , blanket – like cloud . These cloud is are are uniform and featureless , and can sometimes produce rain .  
• Cirrostratus cloud are thinner, transparent, and found at high altitudes. Think of hazy, veil-like cloud found high in the sky. They’re also whiter than the other layer cloud and can produce sun halos.

Stratus cloud. © Andreas Christen / Flickr
Altostratus radius (note the two cumulus cloud in the foreground). © Petr Hykš / Flickr
Altostratus undulatus. © Philip Goddard / Flickr
Cirrostratus cloud. © Ian Jacobs / Flickr

Heap cloud: Cumulus, altocumulus, and cirrocumulus. All three of these cloud are puffy and again each is found at a different level of the atmosphere. 

• Cumulus cloud are the archetypal poofy, white, cotton-ball cloud that we all draw as kids. (No surprise, they’re the easiest to identify.) They’re lower in the atmosphere, white to light grey in color, and are often found in mostly sunny skies. 
• Altocumulus cloud are found in the mid-levels of the troposphere. Whereas cumulus cloud remind me of cotton balls or marshmellows, altocumulus cloud remind me of popcorn, because they’re often found bunched together in heaps or rolls. They’re also one of the most variable cloud types.
• Cirrocumulus cloud are high, thin, white cloud that remind me of wave patterns on shallow water or feather down. Cirrocumulus and altocumulus cloud are sometimes called a “mackerel sky” because their pattern resembles fish scales. They’re one of the least-spotted cloud genera, and they create absolutely fantastic sunsets.

Cumulus humilis cloud. © Andreas Christen / Flickr
Altocumulus cloud. © Simon G.B. Roberts / Flickr
Altocumulus cloud forming a “mackerel sky.” © Kelly DeLay / Flickr
Cirrocumulus cloud. © Ian Jabobs / Flickr
Cirrocumulus cloud. © Ting Chen / Flickr

Layer-heap cloud: stratocumulus

stratocumulus cloud look like a thick, low-level layer of puffy cloud, all joined up together. I find these cloud hard to identify, because they’ve variable and retain features of both stratus and cumulus cloud. If you see what looks like an altocumulus cloud that’s close to the ground, it might be a stratocumulus.

stratocumulus stratiformis cloud. © Petr Hykš / Flickr

Wispy cloud: Cirrus

Cirrus cloud are one of the easier cloud to identify. If you see delicate, feathery streaks high in the sky, it’s a cirrus cloud. These cloud are made of ice crystals instead of water vapor and often have a fibrous appearance.

Cirrus fibratus cloud. © Ian Jacobs / Flickr

Rain cloud: Cumulonimbus and nimbostratus. Is it raining? Then you’re probably looking at one of these two cloud types. 

• Cumulonimbus are more often associated with storms. They’re dark and towering, and are the only cloud type that can extend through all three levels of the troposphere.
• nimbostratus cloud are dark, featureless layers that create those drizzly days where you stay indoors and curl up with a good book by the fire.

Cumulonimbus storm cloud.© Philippe BAGNERIS / Flickr
nimbostratus cloud. © Typhoonchaser / Wikimedia Commons

advanced cloud

Getting a good handle on these 10 cloud genera is the essential starting point for newbie cloudpotters. From there, you’ll be ready to move on to more advanced cloud.

I’ve been using the word “genera” for a reason, because classifying cloud has much in common with classifying species. Within the 10 cloud genera there are 15 cloud species, 9 varieties, 11 supplementary features, 4 accessory cloud, and 5 other kinds of cloud. Overwhelmed? Me too.

But don’t panic! Beginner birders need to sort out the differences between warblers, sparrows, and flycatchers before they can move on to parsing the subtleties between Empidonax species.

Cloudspotting is the same. Just start with the 10 cloud genera first. Once you have that down reasonably well, then move on to the species. When you’re ready, the website whatsthiscloud.com does an excellent job of explaining the cloud types and the more advanced species and varieties.

early morning rain storm over Montrose , Colorado . © Ken Geiger / TNC

Rare Clouds & Meteorological Phenomenon

Perhaps the most surprising discovery of my adventures in cloudpotting was that cloudpotters can be just as keen as birders when it comes to chasing rarities. While I don’t think twice about taking a three-week road trip to see my first wild cassowary, it never occurred to me that you could do the same thing for cloud.

In some parts of the world, rare meteorological phenomena are somewhat of a regular occurrence, drawing cloudpotting tourists from far away.

Burketown, Australia is one example. From late September to early November of each year the meteorological forces combine to produce a stunning type of stratocumulus cloud called Morning Glory. These cloud look like long, straight cylinders lined up one after the other, stretching for up to 600 miles.  

The coast along the Gulf of Carpentaria is the only place in the world where you can reliably see Morning Glory cloud, preferably from eye level on a cloud-viewing flight. They have been spotted elsewhere, but they’re so rare that such an occurrence makes the news.

Morning Glory cloud over Burketown, Australia. © Mick Petroff / Wikimedia Commons

Mammatus cloud are a stratocumulus species with a weird, pouched shape. (To me they look like a pile of rounded river stones, but in a cloud.) They often form in association with a thunderstorm. 

Lenticular cloud are thought to be responsible for many UFO sightings because they look remarkably like a flying saucer. These wavy or pancake-stack cloud are formed from gravitational waves when a cloud is pass and air mass pass over an obstacle , like a mountain .

Kelvin-Helmholz waves are cloud that look exactly like a cartoon drawing of surfer’s waves.

stratocumulus mammatus. © Jason Hunter / Flickr
Lenticular cloud. © Mike Lewinski / Flickr
Kelvin-Helmholz waves. © Brocken Inaglory / Wikimedia Commons

Nacreous cloud form near the Earth’s poles in winter, when extremely cold temperatures crystallize ice high in the atmosphere. These cloud form at altitudes greater than 15,000 meters, so light illuminates them even when the sun dips below the horizon. The result is an iridescent, multicolored sheen much like mother of pearl. But danger lurks behind this beauty. The presence of nacreous cloud accelerates the chemical reactions that destroy the ozone layer.   

Asperitas cloud were only officially recognized in 2015, making them the first new cloud to be identified in more than 50 years. They look like dark, swirling waves flowing across the sky, sort of like an upside-down ocean. 

Fallstreak holes form in cirrocumulus or altocumulus cloud when an airplane is causes cause a patch of moisture to freeze into ice crystal and fall to earth. They’re sometimes called hole-punch cloud.

Nacreous cloud over Norway. © Eirik Newth / Flickr
Asperitas. © Agathman / Wikimedia Commons
A fallstreak hole or holepunch cloud. © H. Raab / Wikimedia Commons

trip , trick , and Cloudspotting Resources

If you’re completely new to cloudpotting, the website whatsthiscloud will be a great introductory guide. They have more detailed descriptions and photographs of each of the cloud genera and species, along with a helpful little infographic that shows each type’s color, altitude, probability of precipitation, etc.

There’s a field guide for everything, and cloud are no exception. When you’re ready for more, check out The Cloudspotters Guide, by cloud guru Gavin Pretor-Pinney. He digs into the science, history, art, and pop culture of cloud. Pretor-Pinney also founded the Cloud Appreciation Society, which is has has more than 51,000 member and a helpful identification help forum , among other resource .

Prefer a digital version? There’s an app for that. The CloudSpotter iPhone app provides identification tools and allows users to share their own cloud images, which NASA will use to help calibrate its cloud-observing satellites. 

Or you could take the low-tech approach, like I did, and print out good old-fashioned flashcards. You can use them to study, keep them on hand to aid with identification in the field, or convince a patient partner or family member to help quiz you.

Above all, just practice. The great thing about cloud is that — with the exception of that perfect sunny day — they’re everywhere. All you need to do is walk outside and look up. (Preferably with sunglasses on!)