Thursday, May 23, 2013

Stable Layer


This is another one of my weather observations. There is always something interesting to paint in the sky.

The sky was overcast with calm winds at the surface. Gravity waves in the altocumulus clouds indicated that there was a stable layer in the atmosphere. The winds at that level were certainly westerly. At the same time arcs of lower altocumulus clouds suggested a significant deformation and stretching process in the wind field. There were even a few spits of rain. Even though the skies were dark overcast overhead the clues were still suggesting that nothing much would come of it. There were patches of brightening skies on the western horizon indicating some thinning of the overcast layers. There were no thunderstorms in the offing so I went and got my easel and palette. By the time I was finished a couple of hours later it was a beautiful and sunny evening.

After painting I checked the radar and a band of strong thunderstorms had developed just east of Singleton. This pattern is typical due to the wave structure of the atmosphere. Other bands of thunderstorms would develop ahead of the troughs of these atmospheric short waves as they rippled along the warm front which stretched west to east across the region. Although it was a clear evening when I finished the painting at least a couple more lines of thunderstorms would cross the lake overnight. The stable layer that I painted was the result of the "calming" of the atmosphere after the passage of a trough and ahead of the arrival of a short-wave ridge. This might sound complicated but it is really quite simple - trust me.

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