Smoke in Sky - The Impact on Astrophotographers!
June 28, 2023
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Introduction
Recently, people have become aware of smoke from regional wildfires impacting their skies.
It has been hard to avoid - First, we saw wildfire smoke from Alberta, Canada, roll into our region and change our blue skies to pale blue or white skies. Then we had smoke from Wildfires in Quebec cast a ghastly yellow pale over the sky - and what was more - we could see and smell the smoke!
Wildfires have occurred much earlier in the year, and they are much more pervasive and impactful than we have seen in the past.
I know it has significantly impacted my astrophoto activities - and I am not alone.
I have gotten a lot of questions about how all this impacts me, and I realized that to talk about this, it would probably be good to talk about a topic that is seldom covered.
While I have discussed HOW astrophotographers capture and process their data, I have never discussed WHEN astrophotographers can capture data!
Understanding this will help to understand the impact of the smoke plumes from all of these wildfires.
I should also note that my points here are related to Deepsky Astrophotography. Other forms of AP will have different needs here.
Capturing Images
People not involved in astrophotography are typically unaware of what goes into making such a Deepksy image.
A significant effort is involved in assembling and configuring the gear needed to capture such images. This includes
The Main Telescope
The Telescope Mount
The Main Imaging cameras
Filter wheels and Filters
Focus Motors and Autofocus systems
Camera Rotators
A Small guide scope and guide scope camera
Dew Strips to heat optics to ward off dew at night
Polar Alignment cameras and software
Guiding software
Sequence Control Software
Then a lot of work goes into developing the methods and techniques for telescope setup and image capture. This capture involves many short exposures taken over many nights - along with calibration data which is also captured.
Finally, image processing is done to calibrate, register and integrate all of the individual subframes into master images and then these are processed to produce the final image.
Putting all of that aside, let's talk about WHEN astrophotographers can capture these exposures.
Can you go out any night and collect the data needed?
The answer to this is a simple NO. Some nights need to be avoided!
Darkness
It has to be dark out. It seems like a no-brainer - right?
But how dark? Night does not come on like flipping a switch. We have a transition with twilight, and then at some point, we have darkness. Astronomical Twilight is when the Sun's geometric center is 18 degrees below the horizon. At this point, we consider things are dark enough for our needs. Astronomical Dawn is when the Sun is once again the same distance from the horizon.
Another factor is that the length of the night changes throughout the year. The shortest night comes with the Summer Solstice, June 21. Where I live, that gives us about 4 hours of useful darkness. The longest nights come with the Winter Solstice, December 21, and it provides almost 11.5 hours of darkness in my area.
This graph shows the length of the night - along with various twilight definitions - selected is the SHORTEST night of the year. (graphic from timeanddate.com)
This graph shows the length of the night - along with various twilight definitions - selected is the LONGEST
night of the year. (graphic from timeanddate.com)
We need to have it dark enough to take our exposures.
Astrophotographers can't start their image capture until we are well into Astronomical Twilight. Conversely, we have to know when to stop our exposures. As we get closer to sunrise, the light from the Sun illuminates particles in the atmosphere, increasing the brightness of the background sky. This will quickly swamp the faint illumination from our targets.
Fortunately, many tools and resources can use when these start and stop times are throughout the year. One such resource is:
https://www.timeanddate.com/sun/
Weather Issues
Clear Nights
We cannot take exposures if it is precipitating or clouds block the sky!
This is also pretty evident: If you can't see the stars, you have a problem! We need clear nights for astrophotography.
When I say clear - I mean CLEAR. Thin cirrus clouds may allow you to see stars visually but negatively impact the quality of captured subframes.
When capturing data, you want a night with no clouds and a low risk of clouds moving into your area. In fact, what you really want is a string of nights where this is true. I captured data from over five nights on some of my best images!
There are some mythical places with dry air and stable weather that have 300+ clear nights a year! Most of us live in areas that have considerably fewer clear nights!
I live south of Rochester, NY - in the state's western portion. Our weather tends to be seasonal and quite dramatic in how it changes.
Rochester, NY was the home of Eastman Kodak - I have always kidded that George Eastman picked Rochester for his company's base of operations as it always had a remarkable 17% gray sky - a great photographic standard!
While the skies may be a wonderful photographic reference, they suck for astrophotography - I get considerably fewer than 300 clear nights a year!
So part of the challenge is waiting for a string of nights with clear skies.
This can be a bit of a guessing game. Astrophotographers use advanced apps and websites to predict the weather and near real-time satellite views to asses and track clouds in their area.
These include:
https://www.astrospheric.com is a Great App for seeing cloud and smoke conditions
https://clearoutside.com/ is another great resource for seeing what nights are good for imaging
https://weather.ndc.nasa.gov/GOES/ Geostationary Operational Environmental Satellites: Great Satellite images that can show conditions in your area.
Screensnap of the Astropheric webpage (click to enlarge)
Screensnap of the ClearOutside Web Site (click to enlarge)
GOES Satillite in Red Visible light shows cloud pattern evolution in my neck of the woods.
How do you decide whether a night is good enough for imaging?
Sometimes the weather predictions and satellite maps are so clear that it is obvious. But many nights are harder to judge. Weather prediction is not a precise science, and wind patterns can and do change.
If you have an observatory, preparation for a night of imaging can be as simple as opening up your dome or rolling off your roof. Shutting down is just the opposite. Both are relatively Simple - and easy. If the night is “iffy,” it may be worth trying, as there is little to lose. Some have advanced automation for their observatories. Clouds roll in, and the observatory’s sky camera detects this, shuts things down until the clouds are gone, and then starts back up again.
I have a different situation.
I set up three telescopes in my driveway each night and must take them back down again in the morning. You can see that process HERE. This involves a lot of time and effort on my part. To go for it, I have to be confident that the night will be good enough to be worth the effort!
To give you a feel for what I deal with, here are some charts of historic cloud cover patterns - for last year and on the average.
This graph show the actual data on cloud cover for 2022 in Rochester, NY( © WeatherSpark.com)
This can be a little hard to read. But it does show cloud cover during the nights. Gray represents solid cloud cover and blue is clear skies. You can see the pattern I live with! During the Winter, we typically have few clear nights and this pattern can be seen here. Things begin to open up in April and shut down again in November. You can see much more blue in the middle of the chart.
This chart show the averages over many years for our area (© WeatherSpark.com)
The averages chart shows the general pattern. July-September is our sweet spot. Winter? Not so much!
Other regions will have other numbers for clear nights, but the weather is an issue for many astrophotographers. When we have clear, calm nights, we are elated! When we have bad weather during critical imaging windows, we are devastated!
Calm Nights
Another weather-related issue is the wind.
We want calm, clear nights. But something we get a clear night that can be windy. The wind can be a problem for some folks. If your telescope is sheltered from the wind by an observatory, you may be able to deal with it better than those fully exposed to the elements.
My scopes are exposed, and I can tell when it’s windy out because my guiding metrics suffer!
I go to a lot of trouble to carefully set up my scope and balance things so the drive can track the sky and my guide scope and camera can detect slight imperfections in the tracking and correct them. It does not take a lot of wind to disrupt this carefully arranged and balanced set of forces. A clear windy night may not be worth imaging for me.
The Moon
The Basic Problem
The sky also has to be free of the Moon.
The Moon is the brightest object in our sky next to the Sun. It’s basically a rock out in space that reflects the light from the Sun - even when the Sun is below the horizon.
When the Moon is out, its light will scatter in the atmosphere and cause the brightness of the background sky to increase. When trying to image an extraordinarily faint galaxy, you need to have some difference between the faint signal of the galaxy and the background sky. If you live in a region with very dark skies, the difference is greater and offers better contrast, allowing targets to stand out more.
When the Moon is out, the target object can become hard or impossible to see.
We all know the Moon goes through phases.
The scattered light may be small when the Moon is in its Crescent Phase. But when the Moon is full, the background sky brightness can swamp our target, and the contrast and details will suffer greatly. A similar effect is seen when viewing in light-polluted skies.
This calendar clear shows the Lunar Cycle we want for astrophotography. The New Moon is on the 18th. Useful imaging could potentially be done from the 13th through the 23rd. (Image taken from the great site Almanac.com!)
This great video shows the phases of the Moon along with liberation. (This great video is taken from the Wikipedia Lunar Phase post)
So Astrophotographers avoid data collection when the Moon is out. This means that the period from about five nights before and after the New Moon is what we want - four days before and after is even more optimal.
Each year has about 12 new Moons - some years have 13. We typically have between 72 and 154 Moonless nights (depending on whether you use 4 vs. 5 nights before and after a New Moon) a year where Deepsky Astrophotography can be done.
This comes out to 20-42 percent of the nights in a year are useful for deepsky astrophotography!
Assuming those nights are clear…
Timing around the Moon
Some nights must be avoided completely because of the Moon. But other nights - when the Moon rises late or sets early - we can sometimes work around its schedule. Lunar tables are a huge planning help here.
Life
So, the Moon is new, the weather is clear, the wind is low - everything is coming together! You are set to spend the night capturing some amazing subs - but wait…
Maybe you:
Have to work in the morning and can’t stay up all night….
Have kids that need to be gotten ready for school and dropped off….
Have to travel for business and are away from your telescope!
Are away on vacation with your family and can’t deal with a schedule that is radically different than your family’s…
You have relatives staying with you, and you can’t just drop everything…
You are sick and can’t do much of anything….
The point is that sometimes Life gets in the way of your astrophotography!
I held off getting involved in astrophotography until I retired.
Before then, I was the CTO of a small start-up company, working with a globally distributed team. That meant there were some meetings I had to have early in the morning and some late at night. I was swamped and had no bandwidth for anything else.
Once I retired, I knew I could seriously commit to astrophotography as I would have the time!
So Life is another parameter that weighs in on your ability to do image capture!
Wildfire Smoke
The Wildfire Crisis in the US and Canada Takes a Devastating Toll
As we approach the peak of summer, the United States and Canada are gripped by a devastating wildfire crisis. Fueled by climate change, the scorching heat waves have set ablaze areas of pristine forests and grasslands, leaving a trail of destruction in their wake. With soaring temperatures and prolonged drought, conditions are ideal for the rapid spread of wildfires. From the dense woodlands of California to the lush boreal forests of Canada, countless communities are on high alert, grappling with the constant threat of flames engulfing their homes and livelihoods. Firefighters and emergency crews are tirelessly battling the infernos, but the sheer scale and intensity of the blazes have overwhelmed their resources. As smoke blankets the sky and ecosystems buckle under the strain, one wonders if we are entering an era with a new “normal."
So now we have another factor to consider as we determine when to capture subs.
Smoke from wildfires can be caught by global wind patterns and carried to locations near and far. This smoke can act like an independent system of clouds - but these “clouds” are formed from tiny particles of smoke from these massive fires. The result can be subtle - like looking through a very thin cloud - or it can be quite substantial, where you can’t see the stars at all!
This is not new.
In the past, we have seen smoke from large-scale wildfires out west hit us during the hottest portions of the summer. This would not happen often, but I have lost integration time because of it.
No, what is new is how early in the year we are seeing this smoke - and how pervasive and impactful this smoke is.
So now we have to dodge the Moon, find periods of good weather, make sure our lives will allow us the bandwidth to collect data, and dodge smoke plumes!
This year (2023), we have had significant wildfires in Alberta, Canada, starting in early May. This is very early, but the fires there have been unprecedented, and with our luck, the Jet Stream picked up the smoke plumes and swept them over the northern portions of New York State. These were bad enough that I lost several nights of imaging.
British Columbia Fires (GOES-18 Fire Temperature, GeoColor Video-06/07/2023 15:00 - 06/08/2023 02:30 UTC)
Then in late May, Quebec caught fire, and the smoke from these fires was NOT subtle. During the day, you could see and smell it in the air. A dismal yellow pall came over our world.
Looking across my front lawn - this was a clear day weather-wise, bit you could see and smell the smoke around you…
Thick smoke from the Quebeck Fires rolling down south…
Smoke from the Quebec Fires. (GOES Satillite imaging)
Why Are These Fires So Bad?
Much of the affected areas have been in a drought for an extended period. There has also been higher than normal temperature. These effects act to zap the moisture from large forests. It is thought that this is a consequence of Global Warming. In the past, what has been lush damp forests have been turned into dry kindling, just waiting for a lightning strike or a careless human to set things ablaze.
What makes this worse is that the fires have been fed by a large, high-pressure system that’s lingered over Canada for weeks now in what atmospheric scientists call a blocking pattern. This is keeping temperatures high and precipitation low.
In addition, along the eastern edge of that block, a low-pressure system has formed in the Northeast. Air circulating around and between those two systems pulls the smoke southward over the Great Lakes, the Northeast, and the mid-Atlantic region.
As we progress into Summer, the Jet Stream often weakens and this may reduce some of the smoke we are seeing.
Fire Maps for June 26 for all of Canada (from Canadian Interagency Forest Fire Centre Webpage)
More information can be found here:
The problem this year has been worse than in previous years. But is this a blip or the new “Normal?”
Time will tell.
While the fires in Canada have been severe, the American West has had significant precipitation this past Winter, and because of this, we may see a reduction this year in the fires that are experienced there.
Who is to say that next year will be a wetter one for Canada and thus reduce the smoke plumes we saw this year?
On the other hand, Global Warming is a highly concerning trend that will continue to push us toward more wildfires rather than less. We have NOT done enough to curb Globa Warming, which should concern anyone who appreciates the world as we know it. Some people see controversy around Global Warming. I follow science - not politics -so you know where I land on this.
Predicting Smoke Plume Coverage
Predicting smoke plume coverage is just like weather coverage. Certain apps will predict and show you developing smoke plume patterns, and Satellite imagery is very helpful here as well.
Astropherics is my favorite app for dealing with smoke prediction. Here is it is in smoke prediction mode (see the red arrow) and I can step through the day/night hour -by-hour.
The Impact on Astrophotography
As you have seen, Astrophotographers have to choose the nights they collect data strategically. They must consider the following:
When darkness falls and what interval is darkest for imaging
Whether the weather will be clear
Where the Moon is in its cycle
Whether LIFE will allow them to commit.
Having everything line up perfectly is a real challenge, and Astrophotographers rarely get the data collection time they would like.
Now we must add smoke patterns to this consideration.
Smoke can be very thin, or it can b very thick.
It can change over a time scale of hours and minutes. In many ways, it is like the weather. You need to predict how winds and smoke plume conditions converge and assess whether they will impact a particular evening.
When the plume is thin enough, you might try imaging. It WILL have an impact. Contrast will be lost, and sharpness will be impacted. But if you have times when the plume is gone or extremely thin - you can get some useful subs.
If the plume is thick - and I have seen it when it was wafting at ground level, and I could smell it - then imaging is out of the question. At its worse, outdoor activities of any kind are out of the question due to air quality issues. This year we have already had far too many of these days, and I expect we will see a lot more before Canada can get its wildfires under control.
This year, these smoke plumes will not just rob astrophotographers of their opportunities to capture data - they will rob everybody of many clear summer days with wonderful blue skies.
In summary, I fully expect the number of new images captured this year will be significantly reduced. I know this is true for myself - and I also know that the few images I get will not have the quality my previous images had.
This - as an astrophotographer - is extremely distressing, to say the least.
Strategy For Dealing with This Smoke
There seem to be two strategies for dealing with these smoke issues.
The first involves better assessing current conditions and identifying when imaging might be possible. This is very similar to what Astrophotographers already do to assess the weather. It will also leverage some of the tools.
We need to factor smoke and wind patterns into the mix - and recognize that finding good nights will be harder than before.
The second strategy has to do with Observatories and automation.
In times of thinner smoke plumes, those with observatories using a modest degree of automation can still find some times when the smoke has cleared enough through the night to capture some decent subs.
Given that I need to set up and take down equipment, I tend to wait until I think I will have a good night. When we have predictions of smoke in our skies, I tend to sit out that night. There is just too much effort involved for what looks like a very small potential gain.
At the same time, , a local Astro colleague of mine opened his observatory and ran on one target all night. In the morning, he has some usable subs. I had nothing!
In my mind, that seems to be the best strategy for a future that may include more frequent and more impactful smoke plumes.
Conclusion
Astrophotographers, especially those living in weather-challenged areas, already have difficulty finding opportunities for capturing good data. Smoke plumes from wildfires have a huge impact on these activities.
When the smoke is thin, we must capture data when we can. When the smoke is thick, we are completely shut down.
If this were just smoke from a local building fire, we would know it is short-lived and will soon be over.
But these wildfires involve hundreds of separate fires covering millions of acres of land. The smoke from these fires is so significant that their effect is even seen in Europe. These fires will not be controlled overnight. It is a tragedy that is playing out on a global scale.
These fires will have a huge impact on astrophotography.
Ahhh - the life of an Astrophotographer is not simple, and wildfire smoke just adds to the complexity of the pastime.
But then again, if you wanted something easy - you would have never become an astrophotographer!
I kid with my Astro colleagues that a core part of Astrophotography is SUFFERING. If you have not suffered, then you are not a true Astrophotographer! One must suffer if you ever hope to create a great image!
I’m mostly kidding when I say this, but it is also kind of true. Many hurdles must be overcome to do Astrophotography well. Those that stick with it seem to be attracted by these kinds of challenges!
Wildfires will make things harder to deal with - we must hope this is NOT the new normal.
Hopefully, this season will pass, the skies will clear, and all of us can be out at night happily capturing photons again!
But as astronomy enthusiasts - and those who firmly believe in the scientific method - we must do our part to push the political class to treat global warming with the seriousness it deserves.
A special thanks to Gary Opitz - our local weather wizard - for sharing with me some key URLs regarding satellite imagery and Candaian Wildfire information!
