"The problem with clouds," my friend Jeff says, "is that their field marks are always different."
For those birdwatchers, butterfly chasers, and wildlife viewers out there, you know the value of field marks in the identification of different species. You cannot simply say (as I do) "It's a marbled murrelet because I say it is," or "It just looks like one, besides, who else would be out here calling in the forest at 4 a.m.?" No, you must offer up some concrete details to support your pronouncement.
Those details come in the form of field marks--the shape of the bill, the facial markings, the pattern plumage (or scales, fur, skin in the case of other animals). If you can say that the bird in your binoculars is a robin-sized bird sporting black wings, a black face and white collar, you can match this to the image in your field guide and feel confident that you have identified a marbled murrelet and not a Xantus's, Kittlitz's, or Ancient murrelets bobbing on the water. If you are patient and methodical, you can probably identify the dozens of species of gulls whose field marks vary according not only to species but also to age, wear and fading of plumage, and stage of molt. If you are patient and methodical
and equipped with a dozen field guides and charts, you still won't be able to pin down every cloud you see.
Which brings me to this weeks cloud, altocumulus undulatus. At least, that's what I think it is. This is a mid-level cloud--I can tell this because there are other clouds--stratocumulus, nimbostratus, cumulus fractus-- that apear to be lower than/below them in my photographs. The clouds have a bit of puffiness to them, telling me they are altocumulus and not altostratus. And, as far as undulatus goes, this variety of cloud has elements (bands in this case) that are arranged in almost parallel lines or wave-like undulations created by wind action. This undulatus cloud resembles ripples, or undulations, made in the sand by the action of tide or ocean waves.
Still, I am not confident in my id because my two photographs match none of the photographs in my
Weather Identification Handbook (by Storm Dunlop), or my
Cloudspotter's Guide (by Gavin Pretor-Pinney) or
The Audubon Society Field Guide to North American Weather, or the two editions of "A Guide to the Sky" poster (by Art Rangno). Nor do my clouds match any of the hundreds of photographs posted on the Cloud Appreciation Society's website. The field marks seem to have changed. Other ac undulatus are puffier, more extensive, more irregular, closer, whiter, photographed with better cameras!
The four photographs below are also possible contenders for the altocumulus undulatus.
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| The clouds in the right corner look like the layered rippling, mid-level clouds. |
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| These are altocumulus undulatus from above--a bit puffier, more extensive, and regular in undulations. |
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| This altocumulus undulatus has very weird field marks. It's a "radiatus" type in an unusual stage of formation or deterioration thanks to cross winds aloft. |
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| This looks like a more mature version of the two altocumulus undulatus photographs at the top of this posting. |
See the problem? I am thinking that any field guide to the clouds, no matter how authoritative, is woefully misleading and makes Accidental Naturalists like me extremely (but happily) frustrated in their attempts to create tropospheric orderliness in a sky of chaos and mutability. Were I not 100% addicted to identifying the clouds I see, I would throw up my hands, pull out my lawn chair and just watch them and marvel at their infinite...yes, truly infinite...variety.
There are some 370,000 different species of beetles, a fact that some like to joke, showed God had an "extraordinary fondness for beetles." Ha!
