Tuesday, July 28, 2020

The Cold Conveyor Belt - The Weather Wizard Behind the Curtain

#0828 "Standing Outside the Fire" Pixels Link

It might be surprising to claim that the last conveyor belt to study is also the most important. Why? How? The flamboyant Warm Conveyor Belt takes heat and moisture energy as it rises northward. The powerful Dry Conveyor Belt transports dry and cool air to the south as it sinks. Both of these actions help to keep the earth in an energy balance. Both are responsible for the bulk of the energy found in mid-latitude storms.The Cold Conveyor Belt is not even wound up with any of the gears in the weather machine.
The Weather Machine
 Conveyor Belts Powering the Weather Cogs
of Swirls and Vorticity Tubes

Ahhh... but the cold conveyor belt controls the location of the surface warm front, the character of the precipitation and more importantly, it is the one that can keep people in touch with the nature of the weather. This will take some explaining.

The Cold Conveyor Belt (marked CCB in the figure as the blue flow) is even a challenge to analyze and diagnose. Typically this important flow is hidden under both the rising and moist Warm Conveyor Belt and even the sinking Dry Conveyor Belt - important partners in the weather dance. The Cold Conveyor Belt can’t even be seen on my go-to water vapour imagery. In fact, my observational platform for the Cold Conveyor Belt is actually Doppler Radar.

By relying on radar the important advantage of event lead time is largely lost. The severe weather forecaster becomes more of a severe weather observer when precipitation is required to witness the occurrence of an event. The patterns revealed on Doppler require precipitation to reveal the conveyor belts. Those Doppler radar patterns in the Cold Conveyor Belt can also be really complex. New Dual Pole Radar is extremely beneficial as well but again the events must already be happening to be revealed by the hydrometers being blown around with the winds.

The Satellite Palette which was largely published through COMET was based on my belief that satellite imagery was very much more than a cloud-no cloud observational tool. The cloud shapes and their characteristics reveal the weather story if one only understands the vocabulary. In addition I was convinced that radar was a lot more than just a rain-no rain observation. Together the patterns revealed in the satellite and radar imagery describe space, time and trends and could reveal what the real atmosphere was really up to.

The radar patterns were potentially more complex and full of artificial artifacts so I started with the satellite. But I believed that the same principles that I had applied to the satellite data could also be applied to the radar patterns. The Radar Palette was born. I thought that the interpretation of patterns was as much an art as a science so it was a logical sequence of study for me. This effort did not get published. I guess we just ran out of time. Meteorologists really liked the Radar Palette over in NOMEK and Scandinavia though.

PowerPoint Splash Landing Page for the Radar Palette
The Radar Palette was based on the Conveyor Belt Conceptual Model. Classic examples of conventional and Doppler radar images were archived from every part of the mid-latitude storm. I used PowerPoint to link the main Entry-Splash Page to these examples. Each link included a description of the classic signatures, how to analyze and diagnose them  and most importantly, what they meant for the weather machine. The PowerPoint approach was clunky but it worked well enough as a prototype waiting for the expertise of COMET to make the material come alive. I just wanted to demonstrate the potential of the Radar Palette. In the Entry-Splash Page the “C” stands for conventional radar, the “D” stands for Doppler while the “DP” was for Dual Pole which was coming on-line in 2007. Here are just a few samples of some of the concepts and radar patterns. I have not thought of this effort in over a decade so revisiting this brought back a lot of memories.

Here is the reference sheet for the Cold Conveyor Belt and its relation to the Warm Conveyor Belt. The cold air always leads in any weather dance. The light-headed warm air will ride over the dense cold air with a typical slope of a rise of 1 kilometre for every 200 kilometres of distance perpendicular to the surface front. Remember that every front is just the surface reflection of the three dimensional deformation zone skin which encapsulates the air mass. If the cold air is doing the soft shoe shuffle northward then the warm air at the surface must advance. If the cold air is doing the stroll parallel to the deformation zone then the front will be quasistationary.

It would take several books to thoroughly explain all of this effort but may I touch on a few things just to give you the idea of why remote sensing is so vital. I will focus on Doppler as conventional radar has been around since World War II and Dual Pole radars are still likely being deployed. The Doppler isodop is very important. The veering or backing of the isodop and the area enclosed can be related to the relative magnitudes of the warm and cold advections in the lower atmosphere.

I have presented “Basic Operational Doppler Applications” just a few times starting around 2007. The analysis and diagnosis of the Cold Conveyor Belt are vital to getting the precipitation forecast right. Important meteorology like warm and cold advection could be observed using Doppler. Differential thermal advections in the vertical could also reveal changes in stability. I named these characteristic patterns with catchy names in the hope that they might stick. I was especially proud of the “Screaming Eagle” pattern. I am still hoping that this material will gain an audience as optimism and persistence can be a good things.
The Warm Screaming Eagle Pattern
If I may, I will reproduce a very few of these patterns and my Doppler applications here. It is not rocket science but it is close. I used these techniques to better understand the hidden Cold Conveyor Belt. The effort was worth it though in light of the fact that the Cold Conveyor Belt helps to controls the phase of the precipitation as well as the longevity of rare but vitally important events like freezing rain. The CCB is the Weather Wizard like the Professor of Oz who hid behind the curtain pulling the strings. 
The Headless Eagle Pattern
 
The Headless Gull Pattern



The Cold Conveyor Belt is best investigated by simple observations that anyone can do. That is the subject for next Tuesday Science. It encourages us all to get out into nature to appreciate the beauty and science of the natural world. That is where we learn best...

Warmest regards and keep your paddle in the water,
Phil the Forecaster Chadwick

PS: There will be NO exam on this material...





Tuesday, July 21, 2020

The Jet Stream - The Bind that Ties

#1061 "Windy St Lawrence" Pixels Link
The dry conveyor belt is intrinsically tied to the warm conveyor belt by the jet stream. In the early years I used the longer phrase “axis of maximum winds” as a general term to describe the wind that was shaping the satellite patterns. The unusual shapes that I was trying to describe and understand on those grainy early 1980 satellite images did not match the Venn Diagrams that we were taught in the Training Branch of the Atmospheric Environmental Service. Those early meteorological cookbooks tried to simplify techniques to better forecast the weather . This was before before computer simulations of the atmosphere really started to improve. The location and characteristics of the jet stream was the number one priority to better prediction of the weather.
A PowerPoint Screen from my Teaching Days
with COMET, NOMEK and EUMETSAT

There were four basic ingredients in the jet stream menu.
Find the dry slot in the comma pattern
Baroclinic zone cirrus streaks
Low cloud discontinuities
Connect the dots located above.

The strongest winds or the jet maxima (the J in the accompanying graphic) were located in the dry slot and downstream from the col.

Using the new tool of satellite imagery and these simple ingredients led to more discoveries. The conveyor belt conceptual model was the first and foremost among those.

The Weather Machine Cogs or Swirls lay down
three dimensional deformation zone skins
 that encapsulate the weather. 
The jet stream is like the broad leather belt in the conveyor belt machine wrapped around the drive wheels of the weather engine. The axis of maximum winds spins up the cyclonic tube of the smoke ring in the trough. The jet then ascends the ridge to spin the anticyclonic tube before exiting into the next system downstream. The jet stream or axis of maximum winds powers and ties the cogs of the dry conveyor belt to those of the warm conveyor belt. If you really want to learn about a system, you need to follow the energy….

I always found it important to go back to first principles to explain how the mid latitude storms were fueled. All of the energy must ultimately come from the sun and this energy needs to be moved around the Globe to keep everything in balance. Every closed system must find its balance. 

Zonal Jet Stream
The sun heats the darker earth tones of the lower altitudes. Those surfaces are nearly perpendicular to the sun’s rays through most of the year. At higher latitudes the earth surfaces are more likely to be covered by reflective snow and ice. The inclined surfaces receive only a glancing exposure to the sun’s rays. The poles do not soak in nearly as much heat energy as the equatorial regions. 

The zonal jet stream results from the temperature difference between the equator and the poles. The jet stream blows from west to east. This thermal wind direction is easy to remember. If you keep your right hand in the warm air and your left hand in the cold air, you are looking in the direction of the wind caused by the contrasting temperature. 

Increasingly Meridional Jet Stream
This zonal jet does not move heat energy around. Weather happens as the jet stream becomes more meridional.  Typically the storms become stronger and slower moving as the jet stream flows increasingly meridional as it plunges southward around deep troughs before rising downstream around the large upper ridge. 

The conveyor belt conceptual model explains how warm air is moved northward and cold air to the south and how meridional flows relate to the weather. 

There is another important source of energy. The energy in the water cycle also comes from the sun. Water evaporated from the earth requires the heat of vapourization to change from a liquid to a gas. The heat of sublimation is needed for a solid to change to the vapour phase. The conveyor belts move water in all of its forms around the globe. The energy inherent in the phases of water moves with those winds as well. 

White and dark blue bubbles on this Canada Day Water Vapour
image are convective bubbles rising off the isentropic surfaces
Water vapour rises in the isentropic ascending flow of the warm conveyor belt. The vapour cools and at some point returns back to either a liquid (rain) or solid form (snow) with the release of that heat energy back into the atmosphere. Those air parcels where the precipitation is created from the vapour, are suddenly heated and they explode off the constant energy surface of the isentrope. These warmed parcels rise like hot air balloons to much higher potential temperature surfaces in the atmosphere. Meteorologists call these ascending air parcels convectively unstable. The release of energy from the change of state fuels the cyclonic swirl, the warm conveyor belt, the precipitation and the vertical convection. Water vapour imagery dramatically reveals those parcels convectively leaving the isentropic surfaces. 

A similar but opposite process can occur in the dry conveyor. Any liquid or solid phase water within the dry conveyor belt can cool air parcels containing them as they vapourize to a gaseous phase. The bubbles of parcels of cooled gaseous water vapour can sink like the proverbially lead balloon. You can feel these cold parcels of air under virga. Evapourating rain drops cool those bubbles of air often before a few of them actually succeed in reaching the ground thus creating a shower. 

The following animation from Canada Day reveals the wealth of meteorological information that may be gleaned from the relative motions of the warm and dry conveyor belts - that is the real weather. 



These are the big energy sources that fuel the conveyor belt conceptual model and mid latitude weather and storms. This energy all comes from the sun... and it happens in an exceedingly thin atmosphere about a twentieth of the thickness of the skin of an apple if an apple was the size of the earth... 

That's enough for today... but it ties the dry and warm conveyor belts together and binds it with the energy from the sun... and yes, I am dyslexic ...

Warmest regards and keep your paddle in the water,
Phil the Forecaster Chadwick

Tuesday, July 14, 2020

Finishing The Dry Conveyor Belt

#2047 "New Beginning Sunrise" Pixels Link 

The conveyor belt conceptual model of the wind patterns found with a mid-latitude low pressure area, is fundamental to the understanding of cloud patterns. Note that the term “cyclone” is frequently used to replace “low pressure area”. The idealized conveyor belts are in the atmospheric frame of reference relative to the low.
The Conveyor Belt Conceptual Model 
The dry conveyor belt (DCB - Orange Arrow) is the contrasting dance partner for the warm conveyor belt in the weather ballet. The DCB originates from high levels and follows the constant energy isentropic surfaces downward as it plows toward the south on the western flank of the warm conveyor belt (WCB). The dry air is relatively dry to start with and becomes drier and warmer as it descends. There are minimal cloud tracers and the atmosphere uses invisible ink to write this part story in the storm. The water vapour is key to diagnosing the DCB as described in the previous post “Reading Water Vapour Patterns“. The croquet hoop and smoke ring analogies can still be used but without cloud or smoke, one must use your imagination to visualize the circulation.
Descending Smoke Ring to Croquet Hoop Analogy
The leading edge of the DCB is also a bowed shaped deformation zone. The anticyclonic branch of the DCB tends to penetrate further south and lower in the atmosphere. This anticyclonic companion flow is drier, lower and warmer that its cyclonic companion across the DCB flow. The cyclonic companion typically turns back northward and rises on the sloped isentropic surfaces. These DCB circulations help to define the character of the cyclonic companion of the warm conveyor belt and the associated cold front.
 The katabatic or inactive portion of the cold front is typically associated with the anticyclonic branch. The warm air above any katabatic cold front is actually descending. Any cloud associated with a katabatic front tends to be well ahead of the surface wind shift and cold front.

The cyclonic branch does not descend as far and tends to wrap around the cyclonic circulation which is the low pressure area for the mid-latitude storm. The anabatic or active portion of the cold front is typically associated with the cyclonic branch. The warm air any anabatic cold front is ascending and thus promoting the development of cloud and precipitation – most of which occurs behind the surface wind shift and cold front.

The col in the bow of the DCB deformation zone separate the weather regimes and the anabatic and katabatic portions of the cold front.

The Water Vapour from June 1st 2020
The area of thew DCB is clear on the
corresponding visible imagery
Flows in the atmosphere are rarely as smooth as flowchart arrows. The dry conveyor belt (DCB) tends to be segmented into pulses associated with local wind maxima that move along the jet stream axis and energize the cyclone. These are called jet streaks and they will be another subject for a blog entry – jet streaks are that important too. This cross section is perpendicular to the WCB flow and shows how multiple DCB bursts might interact. Secondary lines of cloud can be expected where these DCB pulses collide with the cyclonic companion of the warm conveyor belt.  Water vapour imagery is essential to analyzing these DCB pulses. Each pulse will bring a burst of stronger winds toward the ground.

Every line in the water vapour imagery has a story to tell and the conceptual models are your keys to unlocking and understanding the wonder of weather. Meteorologists typically analyze the first pulse of dry air. The other pulses are invisible without the aid of the WV imagery. The movement of dry air is every bit as important as the circulations of clouds.

Here is a weather information site created and maintained by my friends in Boulder, Colorado. I think you will find it very useful.

http://weather.rap.ucar.edu/satellite/ and select  Water Vapor (mid)

That's enough for today... much more to come.
Warmest regards and keep your paddle in the water,

Phil the Forecaster Chadwick

Tuesday, July 7, 2020

Reading Water Vapour Patterns

#1282 "Singleton Sunrise-2013" Pixels Link
Patterns in the free atmosphere are created by the relative winds. These winds shape the weather as well. The system relative winds are the same as those that flow in the conveyor belt conceptual model. Historically we developed the tools to understand these patterns with respect to cloud. In the early days before water vapour imagery, clouds were all that Joni Mitchell and I had and could see.  We had to study them from both sides to really understand what they were saying. Now we can also read the invisible ink written in the skies.

GOES 4
(GOES D through H looked the same -
the number replaced the letter after launch)
Water vapour imagery came along in the 1980’s just as I was starting my meteorological career. GOES-4 was launched in 1980 and could produce imagery beyond the simple visible and infra-red. The water vapour imagery was low resolution and grainy. We were just were learning what it had to say and its "voice" was muffled. GOES-7 (GOES-H before becoming operational) was launched in 1987 and water vapour became really useful then. The same cloud patterns I was using to deduce the atmospheric relative winds could also be found in the higher resolution water vapour imagery – even in the dry air. Amazing! You can do it too.

We have been re-developing these tools from those early days in these Weather Blogs. I will summarize those methods here and you can see how they work on the water vapour imagery from Canada Day. Learning is best done by doing rather than just watching.

In the free atmosphere away from the effects of surface geography:

Linear Shapes

  • Gravity waves are perpendicular to the winds like waves on a lake. Gravity waves are regularly spaced with a wavelength that increases with the speed of the wind;
  • Elongated Langmuir Streaks are parallel to the winds. Generally two to four parallel Langmuir streaks can be found and they are generally larger and longer with increasing wind speed;
  • Deformation Zones located at the leading edge of an air mass are perpendicular to the direction of motion of that flow. The speed of advancement of the air mass is directly related to the increasing curvature of the bow shape

Swirl Shapes
  • Swirl shapes are created by rotation in the atmosphere. The three dimensional “smoke ring” in the atmosphere creates the following patterns which are mainly seen in the quasi horizontal layers of moist or dry air.
  • Wind shear is simply a rotation that is moving faster than the speed of that swirl's rotation. Rotation and wind shear results in curvature in the atmospheric flow. 
  • The jet stream reveals the large scale wave patterns of curvature. An upper trough is where the jet stream curves cyclonically around a southern penetration of cool air. You can think of an upper trough as a large cyclonic swirl and within it you will find smaller cyclonic swirls. An upper ridge is where the jet stream curves anticyclonically around a northern penetration of warm air. An upper ridge is a large anticyclonic swirl. It really is that simple.
  • Align the fingers of your right hand with the elongated features of a swirl while pointing those fingers in the direction of the flow. Your thumb will reveal whether the atmosphere is prone to rising or sinking motion.
Cyclonic Swirls or Vorticity Maxima
  • Aligning the fingers of your right hand with the flow around a cyclonic swirl will point your thumb must point upward. The air is swirling counterclockwise - cyclonically. 
  • Air is typically ascending with and ahead of the cyclonic swirl. 
  • Located to the left of the axis of maximum winds when looking in the same direction that the wind is blowing. 
  • Typically located in an upper trough which is the equivalent of a valley in the atmosphere. Atmosphere relative winds blow with cyclonic curvature through the trough.
Anticyclonic Swirls or Vorticity Minima
  • An anticyclonic swirl aligns the feature edges and the fingers of your right hand and also requires that your thumb point downward. 
  • Air is typically descending with and ahead of the cyclonic swirl. 
  • Located to the right of the axis of maximum winds when looking in the same direction as the wind is blowing. 
  • Typically located in the crest of the atmospheric wave pattern which is the equivalent of a ridge in the atmosphere. Atmosphere relative winds blow with anticyclonic curvature through the ridge.

Additional Concepts
  • Patterns get bigger with time until they dissolve away.
  • Follow the flow and connect the dots where you have obvious clues to the atmospheric relative wind direction. 
  • Situational Awareness and Conceptual Models - If you know the weather situation then you can anticipate the conceptual model that applies. I have only really presented the Deformation Zone the Conveyor Belt Conceptual Models but be assured, there are many more. They typically came to me on night shifts. 
Animation - Time is the Fourth Dimension

Try to view the movement of the elements relative to the mean flow of the system. It can be hard to do. The earth frame motion is the mean flow with the addition of the system relative flow. Conceptual models use the system relative flow which is what we want to understand since the relative winds shape the patterns. Situational awareness and conceptual models will help identify the system relative motion. If you know what the feature is then you know how it typically moves in the conceptual model.
Canada Day 2020 Water Vapour Image
These patterns can be found in both the moisture and the dry air of water vapour imagery and are generated in the free atmosphere by often subtle variations in wind speed or direction. These winds make the weather.

Here are a few of the shapes I saw... it is enough just to find the big ones - they are most important anyway. 

Our understanding of the atmosphere continue to improve. The movement of dry air is every bit as important as the circulations of clouds. Here is a weather information site created and maintained by my friends in Boulder, Colorado. I think you will find it very useful.

http://weather.rap.ucar.edu/satellite/ and select  Water Vapor (mid)

That's enough for today... much more to come.

Warmest regards and keep your paddle in the water,
Phil the Forecaster Chadwick

Wednesday, July 1, 2020

Turtle Nesting Project 2020 Report

The first turtle nest was found on June 5th 2020. It had already been dug up. With COVID and no grand kids around to watch, it was a challenge to locate the turtle nests before predation. We often had five or more turtles wandering around the property. They may not be Ninja turtles but it is still easy for them to elude watchful eyes. The nesting activity has slowed to a stop. I figure that the raccoons got between 15 and 20 nests while I managed to protect 10 - the same as in 2019. The odds of a turtle egg making it to maturity is apparently only 0.3%. At Singleton Lake I try to improve on those odds.

Snapping Turtle Tracks and Nesting Snapper
Northern Map Turtle in Soil
I have provided the turtles with nesting materials that range from coarse sand to limestone crusher run to inch gravel or larger. There is also a lot of dirt to pick from. All of these sites have great exposure to the sun.

The painted turtles seem to like the herb garden and the dirt. The northern map and snapping turtles like the sand and crusher run although the northern maps also go for the large gravel. I did not see any of  the musk turtles this year.

A Pair of Northern Map Nests in Gravel
The trick is to quietly mark the nest during the laying procedure. The turtles do an excellent job of packing the material back down and covering the eggs over. It takes a real Turtle Tracker to find an unmarked nest without the female turtle on it. After they leave I place protection on the nest as shown. The first night or two is crucial to keeping the persistent raccoons out. Layers of protection are gradually removed to ensure good solar heating. By late July the nests are uncovered and nature takes over.
One or two heavy steel grates Topped with Mesh Boards

Some turtles hatch out in September and October but I also see lots of turtles in the spring, having over-wintered in the nest. These turtles all get a free ride to the marsh.
Snapping turtles emerging from the nest - 29 of them at least

Apparently 80 percent of snapping turtle nests get predated. I expect those statistics apply to all turtles. Snapping turtles often live more than 100 years with a maximum theoretical life span of 170 years. The lifespan of turtles seems to correlate with their size. I have read that the smaller northern map turtles can be expected to survive 20 years.

Cultures around the world have various stories about how our homeland has been built on the back of a giant turtle. It is a nice thought that by protecting the humble turtle we are also respecting our homeland. 

Tuesday, June 30, 2020

Enhancing the Satellite View of the Atmosphere

#2059 "Singleton Sunset Reflection" Pixels Link
An important digression before we return to the dry conveyor belt story which is written in the invisible ink of dry  air... it is important to appreciate the importance of satellite imagery and water vapour in particular in understanding the conveyor belts conceptual model and the atmosphere around us.

Historically I preferred using simple grey scale enhancements in satellite imagery. A particulart shade of grey can be related to the brightness or energy returned from every point in the image. A smart enhancement only spends those grey shades over the energy levels that one should expect to observe. That was the premise for those early days when I created special enhancements for the sunrise and sunset periods in order to glean every last bit of information from the visible satellite imagery. The relativity between the brightness of every picture element or pixel in the scene was preserved but greatly enhanced. The resulting pattern could be better interpreted as to what it meant meteorologically just in time for the early morning forecasts.
Enhanced Visible Imagery from 1981 and 1982
The human eye can really only see 30 shades of grey depending on the lighting. In the early days of satellite and computer technology I would struggle to see more than 15 different shades of grey . The images and their messages got fuzzy. If seeing the pattern is a challenge then that shape and the meteorology it represents are probably not worth finding anyway. The analysis and diagnosis of iffy  pixels was not justifiable.

On a colourful note, the human eye is capable of detecting around 10 million unique colours. Of course these colours need to be selected prudently to display the brightness temperatures from the satellite. The use of an excessive number of colours can result in an abstract work of art and science. Meteorologists can get as easily confused as anyone else. The use of these colours can highlight specific meteorologically important quantities and processes that might otherwise be missed in the world and whorls of black and white. I employed a lot of colours in my work with infra-red satellite imagery in those early days.

The water vapour enhancements used by UCAR are suitably linear and simple. They are as good as it gets for use in diagnosing the atmospheric conveyor belts. The subtle patterns and shapes in the water vapour pixel topography are greatly enhanced. The rising surfaces of the warm conveyor belt comprised of high and cold water vapour are displayed in cool shades of purple and green. The sinking dry and warm conveyor belt is witnessed in hot shades of orange and red - artistic earth tones. A linear grey scale is used to exhibit the water vapour surfaces between these cold and hot extremes. This three way use of colour and grey shades reveal to the human eye the very important physical processes that create the weather in our atmosphere. Water vapour imagery taught me about the importance of one’s frame of reference and swirls. The natural patterns are really quite beautiful as well. The science in the art was unmistakable.

Not everyone sees things the same way though. I used a lot of arm waving and right hand thumbs while in the Atmospheric Environment Service Training Branch, in an attempt to explain what the water vapour imagery was saying. Some of that material is included in these Blog Journals. At that time the message of the satellite imagery was competing with the very seductive numerical presentations of the weather. The numerical weather prediction (NWP) was getting much better and prettier by the month. Remote sensing depicted the real atmosphere but there were concerns and deciphering the messages in the satellite data could be challenging.
Two of the several geostationary satellites above the equator

The geostationary satellites parked above the equator provide terrific imagery in terms of time and space continuity. The drawback with this singular view is that layers of high water vapour in the lower latitudes can obscure important meteorological features below. The graphic will explain this concern.
High Level Moisture Obscures Lower Level Processes
In addition, it can be a challenge to "see" the water vapour imagery in the three dimensions that the atmosphere moves in. One needs imagination to envision what is not painted in the picture.

Looking northeast across North America
One day in 2012 during a break with my COMET friends in Boulder, I expressed a dream to make the three dimensionality of the water vapour (WV) more obvious. If we could only use the WV brightness temperature as the vertical axis and turn the water vapour into a 3-dimensional image... wouldn't that be instructive! It maybe took a day for the creative folks at COMET to achieve that dream. Here are the first examples of what the water vapour can reveal in 3-dimensions. The water vapour topographical surfaces could be turned and twisted into any orientation on the computer screen. The atmospheric secrets were obvious when you enhanced for them. The images can still not reveal what is hidden under higher level obscurations but the three dimensional flows of the conveyor belts were recognizable. This imagery could be produced in real time to aid the meteorologist. I was disappointed when few others were as excited as I was about this development. Sadly, it reminded me of my experience with enhanced visible imagery from the early eighties.
Looking southeast across North America
Those same co-workers are not yet retired and are working on interactive displays to allow the curious to walk through the conveyor belt conceptual model (coming in a future blog) among other meteorological concepts. These same approaches will also allow people to stroll through the weather forecast in four-dimensions including time ... imagine!

The natural world is a terrific and fascinating place. Technology may help us to understand and appreciate it before it is too late! This reminds me of Joni Mitchell's “Big Yellow Taxi”.

"They paved paradise And put up a parking lot With a pink hotel, a boutique 
And a swinging hot spot 
Don't it always seem to go 
That you don't know what you've got Till it's gone 
They paved paradise..."

In any event, weather satellites and our understanding of the atmosphere continue to improve. The movement of dry air is every bit as important as the circulations of clouds. Here is a weather information site created and maintained by my friends in Boulder, Colorado. I think you will find it very useful.

http://weather.rap.ucar.edu/satellite/ and select  Water Vapor (mid)

That's enough for today... much more to come. 

Warmest regards and keep your paddle in the water,
Phil the Forecaster Chadwick

Tuesday, June 9, 2020

The Dry Conveyor Belt



#2057 "Deformation Cirrus"
This is the next step in understanding the conveyor belt conceptual model (CBCM) which replicates the wind patterns found with a mid latitude low pressure area. The CBCM is fundamental to the understanding of cloud and weather patterns. The idealized conveyor belts are in the atmospheric frame of reference relative to the low.

Dry Conveyor Belt (DCB - Orange Arrow)        
The dry conveyor belt (DCB) is the contrasting dance partner for the warm conveyor belt (WCB) in the weather ballet. The warm conveyor belt transports heat and moisture northward. The dry conveyor belt takes cooler and drier air southward. Both are essential to the energy balance of the earth so that in the long term the distribution of heat and moisture around the globe is in balance.  Both are also tied together by the jet stream which is the purple arrow in the CBCM graphic.  

The dry conveyor belt originates from high levels at more northern latitudes and follows the constant energy isentropic surfaces downward as it plows toward the south on the western flank of the warm conveyor belt (WCB). The air is relatively dry to start with and becomes drier and warmer as it descends. There are minimal cloud tracers and the atmosphere uses invisible ink to write this part of the weather story of the storm. The croquet hoop and smoke ring analogies can still be used but without cloud or smoke, one must use your imagination to visualize the circulation. 

The leading edge of the dry conveyor belt is also a bowed shaped deformation zone. The anticyclonic branch of the dry conveyor belt tends to penetrate further south and lower in the atmosphere. This anticyclonic companion flow is drier, lower and warmer that its cyclonic companion across the guiding flow. The cyclonic companion typically turns east or even northeastward and rises again on the sloped isentropic surfaces. These circulations help to define the character of the cyclonic companion of the warm conveyor belt and the associated cold front.

Water Vapour Imaged June 1st, 2020
http://weather.rap.ucar.edu/http://weather.rap.ucar.edu/
How does one study something that is dry? The dry conveyor belt is largely invisible on the visible and infrared satellite imagery. Notable by the absence of clouds. This is not the case in water vapour (WV) imagery which senses the top few millimeters of water vapour uppermost in the atmosphere. Now you know why I embraced the lower resolution and grainy water vapour pictures when they first appeared in the forecast office. The patterns and shapes so obvious in the clouds and weather of the warm conveyor belt were also present in the dryness of the DCB. The dry air also moved like a fluid choreographed by the other another important air flow. In forecast operations this required even more arm waving... more than most meteorologists could take.
Water Vapour Imaged June 1st, 2020 - Detail of the DCB

I use the water vapour imagery to summarize the dance moves of both the warm and dry conveyors belts. In the process of summarizing the weather story behind a painting, it is the only piece of data I ever really need to archive. 
Here is the water vapour image that tells the tale behind #2057 "DeformationCirrus". The accompanying graphics will refresh the lessons learned about the warm conveyor belt and the deformation zone conceptual model which is the star of the painting. Next week we will learn even more about the dry conveyor belt (DCB).

Warmest regards and keep your paddle in the water,

Phil the Forecaster


Tuesday, May 26, 2020

Observing Warm Conveyor Belts and Forecasting Your Own Weather


#1717 "Sunset Waves Nite" Pixels Link
This is the last post on the warm conveyor belt before we move on to the dry conveyor belt. Exciting times for sure! The goal is to figure out just what part of the storm is about to pass your location. The warm conveyor belt is the most visible part of that storm and provides the answer. You can do this!

To become an armchair forecaster, first position yourself to look southwestward... more or less. Most warm conveyor belts approach from the southwest more or less, at least over southern Ontario. If you wish to be more exact, note the current orientation of the jet stream over your location and use that portion of the flow that lines up with the warm conveyor belt. Turn your armchair to look into the jet stream. The jet stream guides the storms and the warm conveyor belt and is the purple line in the accompanying graphic.

Apply these tips to deduce the atmospheric frame winds.
  • The deformation zone has a characteristic orientation to the winds in the atmospheric frame of reference – regardless of the spatial scale of the deformation zone. If you are looking into the col, you are looking into the wind. See A Closer Look at Lines in the Sky.
  •  Langmuir streaks parallel the atmospheric frame of reference winds – even though they might look like they diverge similar to crepuscular rays and train tracks… see Langmuir Streaks 
  • Gravity waves your best friend and are everywhere perpendicular to the atmospheric frame of reference winds. The spacing of the gravity waves varies directly with the speed of those winds. The waves also drift in the same direction as the generating winds just like waves on a lake.

Armchair Weather Observation Platform
Now is the really fun part! You need to sit in the armchair looking directly into the approaching warm conveyor belt. Identify a characteristic piece of cloud that you hope to follow for a few minutes. 

Line that piece of cloud up with the window frame or something not moving and watch which way it drifts. In a few moments you should be able to tell which way that cloud is moving relative to your earthly vantage. Since you are already looking into the warm conveyor belt and the approaching storm, you are looking at mainly the motion of the cloud due to winds in the atmospheric frame of reference. 



If that cloud piece is moving to your right ... the cyclonic companion of the warm conveyor belt is approaching. Point the thumb of your right hand upward and see if your fingers align with any of the swirls in the cloud. There could be gravity waves in the cloud perpendicular to your fingers and the atmospheric frame winds. There should also be a considerable amount of cloud. See The Cyclonic Side of Life for more details. 



If the characteristic cloud is moving to your left, the anticyclonic companion is in line with your location. Point the thumb of your right hand downward and see if your fingers align with any of the swirls in the cloud. Gravity waves are likely in any cloud that might be present. There may not be much cloud as well and that is part of the clue. See The Relativity of the Companion Flows in the Warm Conveyor Belt for a look at the anticyclonic companion. 



If the cloud is not moving appreciably either to the right or left, you are looking directly at the col in the deformation zone. Lucky you! If there is no delta void in the cloud on the warm side of the deformation zone, then the companion vortices are less intense than average. As the companion swirls increase their spin speed with a corresponding increase in the velocity of the winds in the warm conveyor belt, moisture is increasingly spun away from the col. The delta shape becomes progressively void of moisture - another important clue to the wind speeds in the warm conveyor belt. These winds bring the heat and moisture energy to fuel the storm.  

It is typical with the approach of the warm conveyor belt that the conveyor belt pattern will continue to move along with the jet stream. You may initially see the cyclonic companion but if the storm is far away, the col and eventually the anticyclonic companion could be what you actually receive as weather when the storm eventually arrives. You will need to repeat this exercise as the storm progresses. It will mean sitting and watching the sky. I know you can do this…

You can also enjoy a satellite view of the patterns if you get tired of looking out your window. I prefer a site created by my friends at UCAR (University Corporation for Atmospheric Research) in Boulder, Colorado. Simply Google “UCAR Real Time Weather” and select the mid-level water vapour image for best results. http://weather.rap.ucar.edu/satellite/  If you follow the storm in an animation, your brain and eye will automatically focus on the relative motions of the cloud features that are created in the atmospheric frame of reference. 

Weather is important and it can also be fun! Enjoy the weather when it arrives ... evaluate your prediction (this is also called performance measurement). Have fun and learn... repeat this exercise daily. Embrace nature... it is very good for both you... and nature. 

In #1717 "Sunset Waves Nite" I recorded the leading edge of the anticyclonic companion in oils. Art and science merge. 

Warmest regards and keep your paddle in the water,
Phil the Forecaster

PS: There is no crime in updating, revising, amending or rewriting any forecast based on new observations when they become available. Doing so just indicates that there is still something to learn from nature and that your goal is to better serve your clients. :>)) Anyone who has never fixed a forecast, has yet to really write one that said something worthwhile and of potential benefit to the client. Thank you for reading and getting this far...