Friday, March 3, 2023

Empathetic Meteorology

#1714 "White Pine Island"
Cloud Patterns within the Atmospheric Frame of Reference
and what they mean

Empathy is important. It is vital to examine a process from the appropriate point of view in order for it to make the most sense. Humans are anthropocentric by nature - which is very unnatural! Ask Copernicus and Galileo about the challenges they faced - great minds who dared to think outside the proverbial box encountering obstacles beyond belief. 

Copernicus developed heliocentrism in 1514 that the Sun and not the Earth was the centre of the "Universe". It was published the year he died. Galileo Galilei (1564-1642) the father of modern science, agreed with Copernicus. Galileo was convicted of “vehement suspicion of heresy” and under threat of torture from the Church. Galileo was forced to express sorrow and to curse his errors .. but I digress... 

Meteorology in Canada flourished out of a necessity for safer air travel - simply to avoid storms. Aviation requires a frame of reference attached to the airports and constant pressure surfaces. A fluid on a rotating, oblate spheroid like the Earth does not care much about any of that. Fluids can be better understood following an empathetic frame of reference moving with the fluid. 

Air parcels follow constant energy surfaces (isentropic surfaces) fuelled by contrasting temperatures between the equator and the poles (see "The Jet Stream - The Bind that Ties"). The average westerly winds of the jet streams in both hemispheres move the storms along but what shapes those patterns? The answer is indeed blowing in the wind and using a frame of reference attached to the storm. 

The purple local wind maximum spins up two, adjacent
 companion swirls

A puff of stronger wind (local maximum in the jet stream and the purple vector in the accompanying graphic) creates two paired vortices. The so-called "cyclonic"  or vorticity maximum (red X) is poleward of the jet maximum (in the northern hemisphere to the left looking downstream). By meteorological convention, the "anticyclonic" or vorticity minimum (blue N) is equatorward of the jet maximum (to the right looking downstream in the northern hemisphere). Use your Coriolis Hand to visualize these paired rotations - your right hand for the Northern Hemisphere and the left hand for Down-under.  

These paired circulations are simply cross-sections through the three-dimensional smoke ring blown by the local jet maximum but this blog is more about the patterns caused by the rotational swirls as viewed in the empathetic, atmospheric frame of reference. (See "What do Smoke Rings have to do with Croquet?" for the three-dimensional  approach)

The shape of the moisture patterns is determined by simple vector addition: 

  • the relative strength of the local wind maximum which determines the rate of rotation of the accompanying swirls; and
  • the speed at which the swirls are being translated along by the jet stream.

I did this work on a night shift sometime in the early 1980s. I saw a pattern in the newly available satellite imagery and simply asked "why?" The real atmosphere was the best teacher I could have hoped for. 

The following graphics are the same for whatever speed we wish to assign to the local wind maximum. The associated weather is of course more intense with the stronger jets. 

In "Rotation is the Key to Unlock Cloud Shapes" I explained how the cyclonic swirl in the atmospheric frame of reference formed an open trough in the Earth Frame. 

The open trough became deeper as either the cyclonic swirl (green vectors within the green box) increased in speed or the speed of translation of the system decreased (purple vector attached to the purple circle). Open troughs generally move quickly and are not associated with surface low-pressure areas - both observations relative to the Earth frame. Open troughs typically produce clouds in the free atmosphere but no precipitation. 

When the vectors of the rotational swirl match the 
translational vector, an incipient low is about to
form in the Earth frame of reference -
the same low-pressure area that
meteorologists analyse on weather maps. 

As the speed of the swirl increases more that the speed of system translation, the location of the low on the weather map shifts in the direction of Coriolis Deflection (to the right in the northern hemisphere). In those situations when the system translational speed reduces to zero, the low in the Earth frame of reference must be collocated with the cyclonic swirl in the atmospheric frame.

The clincher is that the centre of the swirl in the atmospheric frame of reference is exactly the centre of the moisture swirl that we witness in satellite imagery - and that is the relative vorticity centre using meteorologist lingo. That is what I discovered on that night shift while closely examining the grainy, hard-copy infrared satellite image. It was a eureka moment for me that would define most of my meteorological life. 

The swirls in the satellite imagery could be analyzed as vorticity centres. Vorticity centres were a staple of the products found in numerical simulations of the atmosphere. Comparing the location of the vorticity centres in the real atmosphere with those in the numerical, simulated atmosphere could lead to improved predictions especially when strong vortices were involved. 

It was really that simple. My goal was to teach this at Training Branch back in the mid-1980s. I was not successful then but did have some success eventually in Boulder, Colorado at COMET. Some of this work can be found within the COMET online material and it is all free - so the price is very right. I have reproduced some of that material in these blogs because it is so very important in order to understand cloud shapes. See "Cloud Shapes from Rotation" for more on this. The additional influence of wind shear that spins up swirls is required to make a cusp in the cloud formation. 

The identical process can be described for the anticyclonic swirls. 

Open anticyclonic ridge - fast-moving fair weather

Incipient High in the Earth frame of reference when the rotational
speed of the anticyclonic swirl is the same as the speed of translation

The location of the high-pressure centre shifts in the anti-
Coriolis Deflection direction (to the left in the northern
hemisphere) as the speed of translation diminishes
to zero and the high-pressure centre analyzed on the
weather map in the Earth frame of reference is collocated
with the anticyclonic swirl.

Clouds make so much more sense if we use an empathetic eye and watch them from the atmospheric frame of reference. Cloud lines and patterns shaped by the swirls can be easily understood.
The red “X” is considered to be positive or cyclonic (counter-clockwise in the northern hemisphere) rotation of the atmosphere. The resultant cloud edges are actually two cyclonically curved arcs that meet smoothly at the centre of rotation. Pointing your right thumb upward at an “X” also points your fingers in the direction of the cyclonic rotation of the atmosphere.

The following animations might assist you to unlock the door of understanding for you...

The point of inflection is not smooth but becomes a cusp when speed shear rotation is added into the mix. In the following animations, the red X of the vorticity centre is between the two components of pure rotation "R" and shear "S". Both rotation and shear cause the atmosphere to swirl. 
As the wind shear component "S" increases, the sharpness of the cusp increases correspondingly. 
If you practice this just a few times and take the opportunity to watch clouds develop and move, you will quickly begin to understand cyclonic cloud shapes. Follow the cloud edges cyclonically to the cusp where the curvature of the arc changes. The cusp is your centre of rotation; the relative vorticity centre; the swirl and where you begin your empathetic view of the atmospheric moisture.
Exactly the same can be done for so-called anticyclonic circulations except that everything is mirrored in reverse.  Anticyclonic circulations are typically associated with descending air and thus fewer clouds- but the weather is still very important. 

Looking back, this work on the centre of swirls seems intuitively obvious. At the time, it was anything but and the challenges were many and varied. A background in art certainly was beneficial to visualize the atmospheric motions from its frame of reference. In the early 1990s with vastly improved satellite imagery,  I attempted to translate that data with the mean translation. The goal of "King Atmosphere Relative Display" or KARD was to further prove the concepts and assist others to see the bumper car aspects of atmospheric interactions. Some of the effort was completed at the King Radar site near Watershed Farm but again the challenges were large and  I had to resort to hand waving.  

I did so much hand-waving in my time that it became more like bad break-dancing. I never tired of attempting to explain the beauty and simplicity of the weather. I guess I have yet to stop trying as I still empathically have my mind up in the clouds within their frame of reference. I also have more time now to take my paints along with me for the ride. 

There is much more that I could explain but this is enough for now. I hope you can get outside with your Coriolis Hand and watch the clouds go by and appreciate them even more... 

Warmest regards and keep your paddle in the water,

Phil Chadwick

Friday, December 2, 2022

Lines and Swirls Explained

#2713 "Curly Hook Cirrus Sunset"
14x18 inches oils on canvas

As the world paves over paradise, may I suggest that you surround yourself with nature? The sky for doing so is the limit or so the saying goes. Actually, the sky has no limits for natural inspiration and perhaps I might be of some assistance. The sky is always available and all you need is time. 

Start by watching the patterns move across the sky. The translation of the clouds does not have to impact the shapes. The average wind simply moves the clouds along. Without water vapour, the circulations are quite invisible but they are still there.  

Recall that moisture is shaped by relative motions within the atmospheric frame of reference. I have written about this many times but "Down to Earth Meteorology" is a good summary.  Absolute location to another reference frame such as the Earth only makes the patterns harder to comprehend. The shapes reveal the wind and those patterns are readily understandable in terms of lines and swirls. The answer is indeed blowing in the wind. Bob Dylan’s 1962 anthem posed some rhetorical questions about peace, war, and freedom and sixty years later, those elusive dreams have still not been attained. In the example of the atmospheric frame of reference, there is a solution though. All patterns within the atmospheric ocean evolve from that simple puff of wind along with smoke rings. 

I reiterated the foundation for this work in my previous blog, “A Jet Streak with a Paddle”. This current blog will assemble those parts in terms of lines and swirls. I will follow that with the easiest atmospheric example - mare’s tail cirrus.  After that, you are ready to understand every cloud in the free atmosphere – almost anyway. 

The Deformation Zone Conceptual Model complete with
Coriolis Hand Orientations - for reference looking down

In “A Jet Streak with a Paddle” we established:

  • The col of the deformation zone (DZ) is located where the rate of speed increase or decrease is the strongest. 
  • The deformation zone (DZ) associated with a speed increase must parallel the flow.
  • The deformation zone (DZ) in an area of speed decrease must be perpendicular to the flow.

Looking Down as in a Satellite View

The Swirls of the Deformation Zone Conceptual Model 
can be added to the lines. You cannot have lines
without the swirls

Smoke Rings are the Three-Dimensional Manifestation
of the Local Wind Maximum. The Visible Smoke Ring
related to the Companion Swirls associated with the 
wind maximum

Cirrus cloud is almost always in the sky for our entertainment. Cirrus is much more exciting than most meteorologists give it credit for. This post and “A Jet Streak with a Paddle” will allow you to understand what the lofty cirrus has to say.

Cirrus uncinus is a special type of cirrus cloud. The word "uncinus" is derived from Latin, meaning "curly hooks". Also known as mares' tails, these clouds are generally sparse in the sky and very thin. The clouds occur at high altitudes, at a temperature of about −50 to −40 °C. They are generally seen when a warm or occluded front is approaching. They are also shaped by the relative wind!

The curl at the end of the band of cloud is associated with a decrease in wind speed. Within the atmospheric frame of reference, a decreasing wind speed requires deformation zones perpendicular to the direction of the flow. 
Looking Downward on the Curly Hook Cirrus Pattern
In order for the speed to decrease, somewhere upstream the wind must have increased in speed as compared to the average flow of the atmosphere. If the speed of the flow increases, the deformation zones must parallel the direction of the flow. The fingers of your Coriolis Hand when aligned with the curl of the cloud, reveals if the moisture is associated with the cyclonic or anticyclonic companions of the atmospheric flow. 

Typically moisture is found on the warm side of the jet stream. This corresponds to the anticyclonic companion. You might notice that the majority of the mare’s tails are anticyclonic swirls. The wind decreases at the end of each mare’s tail necessitating the axis of the deformation to align perpendicular to the flow.
Painting Looking Upward

You can also monitor the drift of the cloud by the average wind. Using your Coriolis Hand, you can determine if the drift relative to the average wind is either cyclonic or anticyclonic. Point the fingers of your Coriolis hand in the direction of the drift as you watch the approaching cloud.  If the drift is toward your left, your Coriolis thumb points downward and you are watching the anticyclonic companion of the deforming flow.  If the drift is toward your right, your Coriolis thumb points upward and the cyclonic companion is headed your way. Your right hand is your Coriolis Hand in the northern hemisphere. This is another application of the deformation zone conceptual model when the wind aloft is decreasing in speed. If there is no lateral drift in the cloud patterns, then the wind is increasing over you. I wrote about the Coriolis effect in "The Solution to Cloud Swirls Can Be Found in Your Hands". 

Everything begins with a change in wind speed. Everything! The change in wind speed results from a change in temperature which in turn drives the thermal wind which directly results in variations in wind speed. Meteorologists call this wind shear. Wind shear creates deformation zones and vortices but you can call them lines and swirls. It's OK, I do. 
Summary of the Lines and Swirls with a "Wind Maximum"
or Paddle Stroke complete with the orientation of your
Coriolis Hand revealing the sense of rotation remembering
of course that the circulation is really a 3D Smoke Ring in space
Looking Downward

Indeed, the entire Conveyor Belt Conceptual Model can be explained using these simple concepts. The infra-red satellite imagery was "fuzzy" in the 1980s but was still adequate to convince me of these truths based on my experience with the paddle. My artistic background was conducive to revealing the patterns I witnessed in the lake and translating them to what I saw in satellite imagery and the atmospheric ocean. The boundaries between air masses are more than just lines, they are deformation zones. 

There is only one thing you need to know - the local wind maximum is responsible for everything you will see in the sky. The wind maximum can be as large as a jet streak in the jet stream or as small as a gust of wind. All patterns in the free atmosphere can be explained by the local wind maximum which creates nested patterns of lines and swirls.

With thanks to my friend Dr. James Moore and
COMET who published many of my
meteorological musings. 

Warmest regards and keep your paddle in the water,

Phil the Forecaster Chadwick

Sunday, November 13, 2022

A Jet Streak with a Paddle

Empathy might be the most important character. We are not the centre of the universe. It is important if not vital to consider the other frame of reference. Walk a mile in their shoes and keep an open mind. Something that looks complex in your world can become exceedingly obvious in theirs. Take a jet streak or a paddle stroke in a lake for instance… 

One Must Examine Shapes in a Fluid from a 
A Frame of Reference attached to the Fluid
These thoughts and movies played out in my mind, typically on a night shift. The essential concept is that anything in a fluid is shaped solely by relative flows within that fluid. Any three-dimensional location with respect to anything else does not matter. The only frame of reference that needs to be applied is the one within the fluid. I have attempted on numerous occasions to explain this concept along with the following graphics. One memory from a classroom at COMET in Boulder, Colorado was disastrous. Everyone seemed so very confused... But I do not give up easily. 

The atmospheric frame of reference moves with the mean flow of the wind. The atmosphere is always in motion but those motions are not uniform around the globe. It is best to just consider a volume the size of a synoptic weather system. The absolute vorticity field can assist in identifying this but I will leave that for another day. 

In the accompanying graphics, the earth frame winds within the purple box are those measured from a given point attached to the globe. The average of all of these earth frame winds is the mean motion of the atmospheric frame of reference and the first term to the right of the mathematical "equals" sign. 

The winds as measured within the atmospheric frame of reference are those winds within the green box to the right. The relative winds within the atmospheric frame of reference shape the clouds that we observe. Mathematically, the vectors must add up and be identical on either side of the "equals" sign. 

The first graphic has calm winds within the atmospheric frame of reference. The cloud shapes must be simply translated across the landscape with the mean winds. 

No relative Motions within the Green Box of
the Atmospheric Frame of Reference

The next few graphics have a wind in the earth frame of reference that simply decreases a bit. Such a change solely in wind speed can be difficult to measure but the impacts on cloud shape are astounding. The result for me back in the early 1980s was the "Deformation Zone Conceptual Model" that Roger Weldon was talking about. A simple decrease in wind speed results in an obvious line perpendicular to the wind and four vorticity/swirl centres that are both paired across that line and companions on either side of the flow. I struggled to develop clear and concise terminology that was meaningful to meteorologists and the general public as well. The relative spins of these four vorticity/swirl centres control the shape of the line and reveal everything about the meteorology within that portion of the atmosphere. The rest of my meteorological career was defined by that single night shift. 

A Slight Decrease in the Wind Measured in the Earth Frame
of Reference Yields a Convergent Flow in the 
Atmospheric Frame of Reference. 

The Convergent Flow in the Atmospheric Frame of Reference 
becomes the Axis of Contraction in the Deformation Zone
Conceptual Model

Deformation Zone Conceptual Model

The next few graphics have a wind in the earth frame of reference that simply increases a bit. That pattern within the atmospheric frame of reference that develops is very different. A linear structure develops but it parallels the wind direction. The line is still a deformation zone but the conceptual model is rotated by 90 degrees. 
A Slight Increase in the Wind Measured in the Earth Frame
of Reference Yields a Divergent Flow in the 
Atmospheric Frame of Reference. 

The Divergent Flow in the Atmospheric Frame of Reference 
becomes the Axis of Dilatation in the Deformation Zone
Conceptual Model

Deformation Zone Conceptual Model

This leads me back to my first study of fluids and patterns which started with the family purchasing a fibreglass canoe around 1964. A single stroke of the paddle created a situation where the water increased in speed and then decreased while the canoe was propelled in the opposite direction - Newton's Third Law - for every action (force) in nature there is an equal and opposite reaction. The lines that I witnessed in the fluid frame of water were exactly the same as those within the atmospheric frame of reference. Duckweed is the canoeing equivalent of water vapour in the atmosphere. 
The Deformation Zone (DZ) Ahead of the Paddle Push
 is perpendicular to the Flow while
the DZ Behind the Paddle Push Parallels the Flow...
Intuitively Obvious if you are a Canoeist

An identical situation is also extremely important in the atmosphere - the jet streak or a local maximum in wind speed along the jet stream. Dr. James Moore provided the following conceptual model and graphic. I added the deformation zones. 

If the local wind speed is increasing, the deformation zone must parallel the flow. If the local wind speed is decreasing, the deformation zone must form perpendicular to the flow. The lines in any fluid form within that medium reveal everything to anyone who is willing to place themselves within the fluid frame of reference.

As a result, the observation of a deformation zone that is perpendicular to the flow requires that the flow is decreasing in that region of the atmosphere. A deformation zone that parallels the flow similar to baroclinic zone cirrus must be found in a region of the atmosphere where the flow is increasing. These are simple ideas but now you know how and why they work. 

As an illustration, applied to cirrus uncinusis. The name cirrus uncinus is derived from Latin, meaning "curly hooks". Also known as mares' tails, these clouds are generally sparse in the sky and very thin. The clouds occur at high altitudes, at a temperature of about −50 to −40 °C (−58 to −40 °F). The 
curl at the end of the band of cloud is associated with a decrease in wind speed. Within the atmospheric frame of reference, a decreasing wind speed requires deformation zones perpendicular to the direction of the flow. With moisture typically on the warm side of the jet stream which corresponds to the anticyclonic companion, you might notice that the majority of the mares tails are anticyclonic swirls.

Warmest regards and keep your paddle in the water,

Phil the Forecaster Chadwick

Wednesday, October 19, 2022

Tom Thomson Was A Weatherman - Summary As of Now

Tom Thomson circa 1905–10
I started doing presentations about the art and science of Tom Thomson in the mid-1980s. I did not keep count but the number of presentations certainly numbers in the hundreds. This mountain of material has grown into a book that is being blogged a bit at a time. 

Thoreau MacDonald (1901-1989), the son of JEH MacDonald was also a friend of Tom and he wrote:

Thomson’s work would be a fine study for some competent critic, but anyone attempting it should be familiar, not only with every phase of his work but with the country too, lakes, rivers, weather; have them in his bones …

I prefer to be positive... being critical is not my style but my natural science background might bring fresh information to the Tom Thomson catalogue raisonnĂ©. This project will take some years to complete but I am in no rush. 

In the draft of my "Tom Thomson Was A Weatherman" book, I included several chapters describing the meteorology and natural science used to better understand his art. This information has already been written in the "The Art and Science of Phil the Forecaster" blogs which I have been compiling for many years. If you should encounter a term or concept that I do not adequately explain within the context of a particular Thomson work, a search of this site will certainly yield the answers. I will typically include linked references to the required background information with each painting. 

The following is a list of the Blog entries to date accompanied by a representative image and a linked title to the Blog. Thank you for your interest.

Tom Thomson Was A Weatherman

Tom’s Tornado!

Tom’s Tornado Two - Some Science

Tom’s Tornado Three - Some Art

Tom's Summer Clouds

Thunderhead: Pink Cloud over a Lake - Summer 1916

Lightning, Canoe Lake: Summer 1915

Tom Thomson’s Last Weather Observation

Tom Thomson's "A Northern Lake" Was the Belt of Venus Sunrise
Tom Thomson's Black Spruce Autumn 1915 observation of a cold frontal passage
Tom Thomson's "First Snow in Autumn", Fall 1916 - Light and fluffy snowsquall snow laden on drooping balsam fir branches

Tom Thomson's Approaching Snowstorm - actually a snowsquall as contrasted with a synoptic scale winter storm.
Tom Thomson's After the Sleet Storm, 1916 - published 25 years after the 1998 Ice Storm and it brings back many personal memories.
Tom Thomson's Burnt Land at Sunset - the dynamics of the weather was Tom's inspiration. 

Tom Thomson's Afternoon: Algonquin Park, 1915 Studio Work in The Shack - Tom painted this in late November 1914 and one of his last works in the Studio Building before heading to the Shack. 

Tom Thomson's The Morning Cloud, 1913 Plein air sketch from the autumn of 1913. What an unusual cloud!

Tom Thomson's Petawawa Gorges Night 1916. The "fallout" from Creative Scene Investigation requires that "Petawawa Gorges, Night" along with the alternate titles "Sunset behind Cliff" and the "The Coming of the Night" need to be revised. The reality is that Thomson was a morning person and this painting was certainly a sunrise observation of light and shapes.

Islands, Canoe Lake, 1916. Some interesting meteorology and history. Tom Thomson spent some time at Canoe Lake in October 1916 after spending the summer being a forest fire ranger at Achray on Grand Lake. 

Landscape with Snow, 1916. Even more interesting meteorology and history. The flip side of Tom Thomson's “Rising Mist - Heavy Skies” Autumn 1916

Smoke Lake - Summer 1915. This is another of Thomson's double-sided panels and there is a story of weather and confusion behind it. 
The flip side of Northern Lights 1915.

Northern Lights 1915. The flip side of Smoke Lake - Summer 1915. Tom observed and recorded space weather as well. 

Path Behind Mowat Lodge, Spring 1917, The gift to Daphne Crombie includes a lot of science as well. 
Coming soon. 
Early Spring, 1917. One of several with very similar names but lots of interesting meteorology.
Coming soon.

There are many more to come but it takes time to translate the book into blogs ... and I still need to follow my artistic journey -  and catalogue raisonnĂ© as well. I prefer to tell my own story so that any mistakes are my own. The errors are hopefully kept to a minimum.

Warmest regards and keep your paddle in the water,

Phil the Forecaster Chadwick