Maria Mudd Ruth

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Hands-on Cloud Identification

What kinds of clouds are these? Aren't sure? Stratus? Cumulo-something? Do you need a field guide or an app? No.

It's not altocumulus, mid-level clouds with individual cloudlettes the size of your thumbnail when you hold it at arm's length 30 degrees above the horizon. (Some say altocumulus are between one and three fingers wide.

It's not cirrocumulus, higher clouds with cloudlettes the size of your pinky nail (or rice grains some say).

They are larger than my fist....so they could be cumulus or stratocumlus but....

...these are even bigger than my very large outstretched hand. The clouds don't have well-defined edges, flat bases, or the look of cumulus clouds. This leaves stratocumulus--a large, lumpy cloud that forms at low altitudes and is often formed as layered stratus clouds (fog) rise as they move inland over low hills. These clouds come in a variety known as stratocumulus fractus, which are the smaller (factions) of the stratocumulus cloud as it breaks apart or evaporates.

Sure enough, when I checked the National Weather Service's forecast discussion, the morning cloud cover was described as "low clouds" and "stratus" and were predicted to rise, evaporate, and give way to mostly sunny skies.