Lines in the Atmospheric Ocean

# 2570 "Cirrus Sunset from the
Bottom of the Atmospheric Ocean"

In the previous blog "Finding Deformation Zones", I promised more art and less science for this Science Tuesday. I used painting number 2570 "Cirrus Sunset from the Bottom of the Atmospheric Ocean" to illustrate how to best find those deformation zones - but I did not explain the art within the context of that art. The sunset sky from Wednesday October 27th, 2021, was an example of a double cyclonic deformation zone embedded in a very large upper trough of low pressure and a nearly stationary southerly flow. The lines in that sunset sky did not easily reveal these truths and I promised to provide an explanation. 

Enjoying this Singleton sunset made me really ponder the orientation of these particular lines in the sky. The complexity of the patterns really emphasized that we do indeed reside at the bottom of a very deep and very dynamic ocean of air. The answers were not immediately obvious. I need to explain this sunset a bit. 

Observing from our Earthly viewing platform reveals the following. There were at least three bands of cirrus above Singleton with clear skies beyond them at least as far as the western horizon. The far edge of the westernmost cloud edge was sharp and  had to be a deformation zone but something was unusual. The well-defined cloud edge was on the western flank of the cirrus band and the moisture was to the east of the deformation zone. Gravity wind waves were embedded within the three swells of cirrus. Remember that long, wavelength ocean swells propagate great distances from their windy source. I was attributing the three bands of cirrus to be atmospheric swells. 

The meridional flow of the jet stream
 revealed a southerly
flow from the Gulf of Mexico
over all of Ontario. 

The drift of the cloud within the bands was from south so the atmospheric winds had to be southerly. Wind gravity waves embedded in the swells were consistent with the earth observation of southerly winds. Some faint ice crystal virga wafted toward the ground while catching the last rays of the setting sun. These trails of virga were in front of the cirrus swells from my vantage. The augmented updrafts where the crests of the wind waves overlap with the crests of the swells, are where you are most likely to find virga. Weather typically exhibits these wavelength properties. 

The dark sunset colours low on the horizon were the glow of the setting sun catching dust in the boundary layer of the atmosphere, stirred up by a daytime of wind and human activities. Smoke and the exhaust of industries from around the busy ports of the Great Lakes would easily explain those somewhat murkier colours. 

To complete the diagnosis of the sunset sky, I would have to consult the view from space. The water vapour imagery confirmed the orientation of the deformation zone over Singleton. But the weather story was even more complex. I was viewing just a small portion of a much larger double cyclonic deformation zone. That line in the sky was associated with an upper cyclone near Timiskaming and a second low well southeast of Cape Cod. Recall that double cyclonic and double anticyclonic deformation zones tend to be nearly stationary with respect to the globe. The next morning dawned cloudy and the satellite imagery confirmed that the pattern had even retrogressed toward the west, bringing the overcast skies with it. The jet stream was in a highly meridional flow pattern consistent with that expected from a weakening flow associated with climate change. 

The area of the water vapour imagery where I sketched in the double-cyclonic deformation zone conceptual model, shows a stronger northeasterly flow actually sinking as it headed southward. The cyclonic x's were actually 3D vortex tubes stretching through the depth of the atmosphere. The moisture over Singleton marked by the little yellow star, was actually rising as it headed northward. This pattern was not moving far but was likely to shift to the southwest with the stronger winds as I noticed the following morning. 

Classic Water Vapour Imagery revealing 
the Meridional Flow Pattern

The highly contorted flow revealed by the water vapour imagery, was typical of the wave number seven of the weakening jet stream. Instead of following the lines of latitude as a zonal, strong current of air, the jet stream was more likely to follow the meridional lines of longitude northward and then southward again in a series of ox-bow lakes. That kind of pattern was over Singleton in that sunset sky and it also told the story of climate change. 

This sunset weather story was unusual in that the weather was approaching Singleton from the east. The typical progression of weather from the west was upset and I think this would cause the viewer some anxiety although they might not really comprehend why. I remember stories of ancient peoples being terrified at the sight of an eclipse. We are not much different. At one time, these strongly blocked and convoluted patterns were very rare. 

RGB imagery like this Nighttime Microphysics
Image, combines several channels and typically
complex combinations of channels to the red, green,
and blue colours. The physical properties of the
earth-atmosphere system are better understood
by using both colours and tones to paint the data.

Satellite imagery reveals details and complexities that could keep professional meteorologists entertained for days. I know that from experience! Most people should not venture down that rabbit hole. Always remember that the atmosphere is a complex three or four dimensional flow. It is sufficient to just understand the big picture, at least to start. 

The clouds always tell the truth even if humans might not like to hear it. I paint what I see and nature always makes sense even if it might take some effort to unravel the lines in the sky. 

Keep you paddle in the water and warmest regards... 

Phil the Forecaster Chadwick