Weather Warm Ups (Inversions)

Just sent another article to Canadian Aviator magazine. Here it is in its “raw” version.

An anvil and a fully developed thunderstorm. This guy hit the tropopause hence the blacksmith looking anvil. I called this inversion or isothermal layer a tropopause inversion. I took a pic of this “bad boy” over Montana. It flirted to FL 460 or so, well above an airliner’s maximum height.

An anvil and a fully developed thunderstorm. This guy hit the tropopause hence the blacksmith looking anvil. I called this inversion or isothermal layer a tropopause inversion. I took a pic of this “bad boy” over Montana. It flirted to FL 460 or so, well above an airliner’s maximum height.

Temperature Warm Ups (Inversions)


A Weather Warm Up (Inversions)


Temperature Warm Ups Aloft

Any pilot knows temperature decreases about 2°C per 1000 feet, but meteorologically inquisitive pilots want to know more about lapse rates and what exactly is going on aloft. I recently gave two talks to local COPA chapters on lapse rates. They discovered weather balloons launched twice a day from over 900 sites globally gather information while ascending to about 100,000 feet where the balloon bursts and tumbles back to earth slowed by a parachute. From these soundings, air is found to sometimes warm with height. These inversions occur in four different scenarios.

Nocturnal inversion. During the night under light winds cooling is more rapid over land than over water. This nocturnal cooling leads to stability in the lower layers as an inversion develops and may lead to the formation of low cloud or fog. Smoke rising in these inversions spreads out horizontally or even sinks as the warm air seeks the cooler air below. Any place with a smoke stack will depict such an inversion, however, unpleasant smells may ensue. I frequently see those low based plumes from pulp mills while flying into Vancouver from the east. Smoke from wood stoves will also form a plume during such an inversion, but the smell is much more pleasant. Nocturnal inversions generally mean smooth flight conditions, but sometimes non-convective low-level wind shear (LLWS) can be present when a surfaced-based inversion results in the development of a low-level jet maximum at the top of the inversion. This inversion decouples the wind just above the surface and allows the winds to accelerate unencumbered by surface friction. Nocturnal inversions can trap many pollutants and moisture, possibly resulting in IFR conditions. If you fly up north during the Arctic winter (think long nocturnal night) you’ll witness dramatic inversions.

Years ago, at a weather conference in Winnipeg, I met a grape grower from the Niagara, Ontario region. His grape-growing operation included hiring a bi-wing aircraft with lots of parasitic drag to churn up the nocturnal inversion, pushing the warmer air to the ground so the grapes would not freeze. Many growers also employ expensive helicopters to do the job. These inversions can also bend ground-based weather radar beams during early morning. The beams are deflected toward the ground giving false returns called anomalous propagation.

Frontal inversion As warm air overrides a cold air mass, a frontal inversion sets up. At the surface during winter below-freezing temperatures exist, but as one ascends, an above-freezing layer develops, on the order of a few hundred feet to several thousand feet thick. Temperatures then decrease to below zero on top of this inversion. Because of this scenario, snow falling through the above-freezing layer turns to rain. The rain then falls into the below-freezing layer near the surface. Depending on how deep or warm this above-freezing layer is, either freezing rain or ice pellets will form which is conducive to serious airframe icing.

Years ago, during a flight from Halifax to Moncton in a Navajo, we encountered light-to-moderate icing in the climb, but an advancing warm front pushed above-freezing temperatures in a thick layer from 4,000 to 8,000 feet with balmy +5° C temperatures. We stayed in this layer until our descent into Moncton and literally watched the ice melt and wash away.

Subsidence inversion Air sinks within a high pressure system, causing air to heat up due to adiabatic compression. This heating eventually causes clouds to dissipate and is why clear skies are associated with a high pressure system.  The sinking (and warming) of the air slows down closer to the surface of the earth, resulting in an inversion in the lowest layer of the atmosphere (typically several thousand feet in height). Clouds may be flattened by this inversion or break up. Stratocumulus is a very common cloud associated with subsidence inversions. Sometimes, this inversion may be so strong that it traps the low-level moisture busting forecasts calling for sunshine!


Often, on descent, I mention the temperature to my flying partner when I suspect a subsidence inversion. I point out that at the cloud top, the temperature will be warmer than the temperature in the cloud. Sure enough, one can watch the temperature sway from, say, plus 6° C at cloud top, to well below freezing a couple of thousand feet inside the cloud. This goes against the standard logic, which says that temperature should increase on descent. The potential for airframe icing exists when the subsidence inversion traps lots of moisture. If you fly near open areas of water such as the Great Lakes during late fall, winter and early spring you may encounter heavy icing conditions in this moisture laden cloud.


The last inversion comes to a surprise for most. Many learn the top of the troposphere (tropopause) has an isothermal layer, but a significant inversion may be present due to warming from ozone in the stratosphere. I am constantly pointing this out to my flying partner (yes, sometimes I get funny looks) and I try to drive it home when teaching new hire pilots who will fly at tropopause heights. The temperature may be -60° C and within minutes it rises to -54°C meaning you flew above the tropopause. On a recent flight from Frankfurt to Calgary at flight level 380 the temperature went from -70°C to -54° C. I haven’t seen such frigid temperatures in a while so I took a picture of the readout. This inversion is why anvils form from thunderstorms.

A frigid outside temperature of MINUS 70 Celsius.

A frigid outside temperature of MINUS 70 Celsius.


There are four types of inversions: nocturnal, frontal, subsidence and one at the tropopause.

Inversions imply stability, but LLWS may occur during a nocturnal inversion.

Warm air aloft and cold air below indicates stable conditions.

Four inversions: subsidence, frontal, nocturnal, and at the tropopause.

Four inversions: subsidence, frontal, nocturnal, and at the tropopause.

Winter warm front and its associated inversion.

Winter warm front and its associated inversion.

Canada and Great Britain plot upper air data on charts called tephigrams, but south of the border they are labelled Skew-T log P diagrams.

You won’t find these plots on NAV CANADA or Environment Canada’s site, however, the university of Manitoba and UQAM (Université du Québec à Montréal) tap into this source.

Many sites and universities supply data from upper air soundings.  

Doug Morris is a B787 captain/certified meteorologist. His weather book, Canadian Aviation Weather, has a great chapter on lapse rates.

Doug recently published an American aviation weather book, Pilot Weather: From Solo to the Airlines.

Nav Canada Update Needed

My previous post depicts what I wrote for my weather column. Below is what made the cut. If you freelance, be prepared to have things changed, altered and mutilated. That’s show biz!

Oh, it looks like I submitted the wrong website address for Pilot Weather. Shoot! It should have been

Pilot Weather is selling like a hot cake. Canadian Aviation Weather needs a boost. Anyone?


Crickets, Warts and Cow Patties

A pending Canadian Aviator article

You probably thought I would be talking about unique weather lore with this title. Sure, male crickets chirp at different rates according to temperature. Found on the web... “to convert cricket chirps to degrees Celsius, count the number of chirps in 25 seconds, divide by 3 and then add 4 to get the temperature.” But “crickets” also denotes silence or NORDO (No Radio) for us pilots. It’s what I experience from my weather blog, feedback from this column and my requests to update NAV CANADA’s weather website.

About six years ago while researching for my weather book, I approached NAV CANADA regarding their archaic weather website. For years, it’s header broadcasted its emergence in 2006 and revision in 2007. But nothing has been touched since. Truth be told, they recently removed the header stating its birth date maybe because some of us were raising eyebrows. Every tab I examine has gaping holes.  “PIREP not available” is found on the PIREP tab for most regions. Have pilots given up? And why can’t I get a high-resolution surface analysis chart? The same one is available on Environment Canada’s site. And why do I have to type in the four-letter ICAO code for METARS and TAFs when the three letter IATA code would suffice since they don’t supply weather outside the Canadian border? The satellite pictures are poor quality, the weather radar does not supply cloud tops in feet and there are more legal disclaimers than there are weather tabs. It’s probably the same reason why Environment Canada persists in calling it ANAL surface for surface analysis. I know many of you gave up and have moved on to other sites/apps, mostly American. We are losing our Canadian meteorological identity. At one time, 9 out of 10 initial conversations began with the topic of weather and that included pilots. Now when an quiet/awkward moment occurs we all reach for our cell phone. But at least we have the TROWAL (Trough of Warm Air Aloft) to reference an occluded front. That is as Canadian as Tim Hortons. Sorry to come out punching with such a negative overtone. To prove I am not all sour and not just another high time crusty ornery captain, my enRoute magazine column will have an upbeat take on pilot hiring - if there ever was a time to become a pilot, the time is now! Okay, back to my stormy take on weather politics.

Over two years ago, I attended an aviation weather conference in Montreal geared for you, the pilot. This three-day seminar consisted of a room filled with meteorologists, dispatchers, academia and one pilot, moi. There I challenged NAV CANADA’s weather liaison why their weather site has not been updated. His lips moved and all I heard was blah, blah, blah. Funny, I could recruit two young computer whizzes on Friday from any Canadian college or university, feed them pizza, beer and legalized Canadian marijuana and they would have a gleaming weather website by Monday morning.

To fly safe, you must challenge and query on a continual basis. Weather and aviation is dynamic so why aren’t you challenging the norm regarding an updated weather website? Are we Canadian aviators that inert? I give the site D+ for disappointing and a disservice.

But it doesn’t stop there. I have been trying to get Transport Canada to acknowledge my weather book, Canadian Aviation Weather, as a viable alternative to a book written over four decades ago, the Air Command Weather Manual a.k.a the ACWM. Don’t get me wrong, this monochromatic book geared for the military is excellent when it comes to theory, but is defunct of aviation forecasts or how to read a METAR. This weather fossil, albeit well written, is pre-internet, smart phone or lap top. Yes, it’s that old and yet the book is the number one seller for aviation meteorology in Canada.

Because my book is not government published the standing policy is Transport Canada can’t/won’t acknowledge it. It is why most flight schools and colleges are reluctant to take it on because their curriculum is geared to questions and material supplied from the historical ACWM. To paraphrase one Transport Canada employee’s take on things and to offer up an explanation why status quo rules, “My grandfather used to say, don’t touch the cow patty, it will only smell worse.” How is that for mandated safety? He admitted to low staffing levels, but claimed my book is being (might be) tagged in their database as a reference for hundreds of exam questions.

I too worked for the federal government and realize the frustration. Over 30 years ago, I was getting an annual “route check” on the weather desk. The supervisor asked what I would like to see or accomplish as a forecaster. I wanted to close the huge gap between weather and the pilot. Sadly, that bridge has never been built nor is it on the drawing board.

My aviation career is slowly unwinding. I teach and write for that young lad in Prince George, British Columbia learning to fly, or for the mother of three changing careers in Quebec City, Quebec flying a Navajo or for that seasoned helicopter pilot flying out of Churchill, Manitoba. After all, the company I fly for also has meteorological warts. They still reference the METAR and TAF as SA (Surface Actual), FT (Terminal Forecast) and FC (a short Terminal Forecast). The system changed 22 years ago, when I was hired! Yes, I’ve been asking. But every large organization has warts. It’s how my friend described his airline that launches from the heat of Dubai, U.A.E. This A380 skipper nailed it with the wart analogy.

To a quote an instructor, pilot, and mentor for young aspiring pilots, “What underlies this malaise and failure to respond to changing conditions and requirements in aviation?

A kick start and wakeup call is in order…”  As an aviator challenge the norm. Take up the quarrel and poke those cow patties.

Doug Morris is a B787 captain, certified meteorologist and wrote Canadian Aviation Weather.  His latest book, Pilot Weather: From Solo to the Airlines is hot off the press catering to pilots south of the border

Time for Weather

Here is the latest found in Canadian Aviator magazine. I called it "Time for Weather" but it was called "When the Ball Drops." Every pilot should make their way to Greenwich to experience where time starts. 

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Pilot Weather book coming soon!

Coming aviation weather book for American pilots...Pilot Weather: From Solo to the Airlines. ETA is September 2018. This book will include a glossary of over 550 entries and will be in full colour  (Oops, I meant color for my friends south of the border). I have hit a meteorological wall trying to convince Canadian pilots that Canadian Aviation Weather is the best weather book out there, so it's time to move south of the border. "Trumpland" here we come!


Wet Microburst

Over Great Slave Lake (North West Territories) in a DC-3 during microbursts. 

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A former student Jamie MK from the Brampton Flight Centre is building time with Buffalo Airways (think the iconic show Ice Pilots) in a DC-3. Notice the outflow cloud and the wave of water created by the intense downpour. Can you imagine trying to land with this parked over an airport?  Or worse yet, training to land a float plane near the dramatic walls of water.

Canadian Aviator (July/August) The Way the Wind Blows

Looks like my column made it to a two page spread instead of 1.5 pages sharing space with an ad. Unfortunately, the  pictures still don't get captions, but I will take the upgrade. 


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Again, the pics are missing captions. The two radiosonde pics originated from Sable Island. I spent a month out there when I had hair. Plus, we used to buzz the Island when we finished our cable patrol in a Navajo. The top right pic depicts 201 winds I encountered in the Airbus 320. (Top left corner of the pic). 

Again, the pics are missing captions. The two radiosonde pics originated from Sable Island. I spent a month out there when I had hair. Plus, we used to buzz the Island when we finished our cable patrol in a Navajo. The top right pic depicts 201 winds I encountered in the Airbus 320. (Top left corner of the pic). 

Thule (Greenland) Albedo

Thule's white runways

Thule's runway 08 degrees True - 260 degrees True

Thule's runway 08 degrees True - 260 degrees True

On page 5 of Canada's best written weather book for pilots (ahem), it is mentioned, "the asphalt runways in Thule, Greenland are painted white to enhance albedo and prevent heating of the permafrost beneath the surface." The topic of unique airports came up while flying over Greenland after we almost diverted to Moscow on a recent New Delhi to Toronto flight. My F/O air dropped this pic to me. (It turns out this same pic is on the internet). When looking at the Jeppesen approach charts there is no mention of the runways being white. Something a pilot should know when breaking out from an ILS approach and seeing a white runway. Think slippery.

Thule is so far north, the runway headings are in True. It's just short of 10,000 feet long. 



Cover design for pending weather book

Just thinking out loud as far as a cover design for a new weather book aimed at our friends south of the border. The completion has been painfully slow. But with the addition of an additional graphic artist there is light at the end of the tunnel. Still hoping for an early summer closure.

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Canadian Aviator (Mag) May/June 2018 METAR Diversity

In the latest edition of Canadian Aviator, I discuss how METARS around the world are not created equal. A METAR is the largest staple for any pilot's weather briefing, but many pilots are shocked to learn they actually differ around the world. This article will broaden your METAR horizon. Of course, I included an in-depth chapter in my book as well. 


New cloud discovered (Cumulus Erectus)

If a pilot starts making reference to how clouds look, then an eyebrow should be raised. If you hear, "hey, that cloud looks like a bunny rabbit" then suspect an hypoxic state from oxygen deprivation and tell he or she to "go on oxygen!"

But how do you respond when a pilot says, "hey, that cloud over there looks like a big (ahem)!"

F/O Brent was excited to fly with me (no, not that kind of excited). He knew I was a meteorologist and wanted to share a couple of pics he took over Colorado. Most have heard of cloud seeding using silver iodide to suppress the development of a thunderstorm. Maybe viagra was used instead for this cloud?

Even though I can't claim ownership to the pics, I will stake it's nomenclature, Ce (Cumulus erectus). This "unique cloud" is actaully caused from the extreme late stages of a dissipating cumulonimbus. (Seriously).


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