With an ocean to the west and mountains to the east, we live in an excellent region to see a variety of clouds. Basic cirrus, nimbus, stratus and cumulus clouds are on view regularly, sometimes all at the same time, along with mountain-capping lenticular clouds, ground clouds, fog, linear cumulus clouds along the spine of the peninsula, the occasional anvil cloud that brings a thunderstorm, and dramatic mackerel skies when a storm approaches.
|As storms approach, the arriving nimbus (rain-bearing) clouds may be preceded by regularly spaced cloudlets, called a mackerel sky, for the appearance of fish scales in the cloud pattern.|
Every now and then something less common appears. Late last fall, December 11, 2013, a striking shadow cast across clouds to the north of Naselle Ridge as the sun rose. It lasted only a few minutes, as the planet rotated east. For those few minutes, sunlight streamed under the clouds, and a shadow from the mountain appeared on clouds north of the ridge as a dark wedge across the sky.
|Clouds regularly cast shadows on clouds. Less common is the mountain shadow on clouds, at least on the coast. This shadow was seen in early December 2013, when a shadow from Naselle Ridge was cast on clouds at sunrise.|
In late spring, coming across the 101 bridge from Astoria at sundown, we saw unusual clouds over Cape Disappointment, and stopped at Chinook County Park to look at them as the sun set. They looked like sets of waves, curling over in a long row. These are Kelvin-Helmholtz Instability waves, which appear at the interface between a calm layer and a turbulent layer, in this case in the atmosphere. What was even more unusual about this sighting was that the turbulent layer was underneath the calm layer, so the distinctive curling ‘waves’ were upside down.
|One of our commonest cloud types is the low to mid level cumulus cloud. in this image, the cumulus cloud is growing vertically, and if the air is very warm, could turn into a thunderstorm.|
Complex cloud layers make very striking dawn and dusk skies. It’s not uncommon to see high cirrus clouds (thin wispy clouds at very high altitudes), with nimbus or stratus layers beneath (thick dense clouds in horizontal layers), and beneath these, puffy scattered cumulus clouds. The evening sky showed a combination like this over Willapa Hills just the other day as the sun set.
Keep a camera handy and watch the sky, dawn, day and dusk. You never know what striking new cloud formation or combination will be visible. As Jack Horkheimer, host of Star Gazer, says, ‘Keep looking up!”
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