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Meteorology (Weather)/Layers of Clouds


QUESTION: Hi-- I live in Berkeley, California, right in the direct path of the clouds rolling in through the Golden Gate. Many an afternoon I've spent lolling in the backyard, watching the clouds. So this has led to some questions.

Sometimes I'll see clouds doing what I think of as roiling, where the edges scallop and twist and are in constant motion; it's mesmerizing. So I watch for that a lot, and then I began to realize that at least sometimes what I was seeing was actually more than one layer of clouds moving differently, so it was almost like a moire pattern.

So here are my questions:

1. Do single clouds ever do that, make fantastical patterns around their edges as they dissolve and shift....?

2. How many layers of clouds can there be?

3. How thick are these layers actually?

4. How can two (apparently) thin layers of clouds, being (apparently) so close to each other be being blown in completely different directions?

and 5. How can I visualize all of this accurately?

Thank you,



You can get roiling in cumulus clouds and clouds diminishing and increasing over very short periods of time:

There can be several layers at a time:

The atmosphere is composed of many different air currents; at times some of these are very close to each other and can be going in different directions.
The layers can be from 20 feet to a thousand(s) of feet thick.

---------- FOLLOW-UP ----------

QUESTION: This was such a terrific answer, so thank you again.

I'm just wondering what causes that roiling? Why some clouds and not others?


"Rolling" clouds typically occur along a gust front that immediately proceeds a "squall line" which is a line of thunderstorms.

---------- FOLLOW-UP ----------

QUESTION: Hi Donald--

I actually did mean "roiling," not rolling! I may be using it wrong, but what I mean is, like, most clouds appear to have relatively fixed edges, but some, the ones I'm asking about, have edges that are in constant motion, curling, etc. How come?

(and thanks again for the answer because though it wasn't an answer to my question, it was pretty fascingating on its own!)

Hi Lily

Sorry for the confusion!

"Roiling" clouds as:

are caused by a turbulent atmosphere:

For more about clouds:  

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Donald Rosenfeld


Any questions (except private) answered from the 1st grade level on up pertaining to any aspect of Weather. I am a 20 year member of the American Meteorological society and a long time forecaster of eastern United States snow storms and Hurricanes.

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