Bigburner Call out Wind, Thermals, topography

[Uncle Lou]

So, it's been a while since we had a BEAST call out. I had the good fortune to spend a couple hours on the phone with Erich, aka Bigburner. He has been around the BEAST for a long time and if you were paying attention he is a great hunter AND he is not just a firefighter, but get calls to forest fires. He is also a land manager, and forester. The man gets called to handle big burns and is the lead man.

Having said that he looks at topography and wind like second nature. I always felt like I had at least a half of a brain until I spoke with him. Erich has a big brain, and I found him very grounded. Good BEAST and good person. So I asked him to address some simple questions and topics and he obliged. He has prepared some information for us to digest that should be very beneficial to the topic of wind and thermals.

I think you will all find this very informative and helpful.

Erich, the BEAST is ready.

[Boogieman1]

All ears, let errr rip BigBurner

[Uncle Lou]

All ears, let errr rip BigBurner

Crap, I thought I mispelled it, but you did.

Here is a short read while we wait.
viewtopic.php?f=287&t=51878

[Bigburner]

I will post up some info tomorrow morning. I appreciate the opportunity. Didn’t know that a conversation with Lou would prompt a call out but I put a lot of work into putting a digestible amount of info together without getting too into the weeds. Standby and Thanks all.

[KLEMZ]

Definitely looking forward to this!

[oldrank]

Sweet. Lets see it !!!

[Wolfofmibu]

Let a rip!

[Jackson Marsh]

Looking forward to it.

[Bigburner]

I was asked by Uncle Lou a few weeks ago to prompt a discussion about thermals, winds weather and topography. Just to give you some background, other than a identifying myself as a lifelong hunter/ outdoorsmans/ woodsman I’ve been a resource manager and wildland firefighter and fire manager and instructor for the past 20 years. The purpose of this is to pass along a small bit of professional knowledge that Is a critical skill to my every day. From a planning standpoint, part of my job is creating fire prescriptions to meet objective in resource management pertaining to wildlife, forests and vegetation. I then implement these plans with state, Federal and NGO cooperators using fire as a management tool. Understanding of weather and topography helps me predict what will happen over a broad landscape and how fire will move, what intensity it burn at, how the ecology of the area will be affected and from a safety aspect provide the best places for my people to be from the point of ignition to suppression. It can get your head spinning in a million different direction. All of this must be done in the confines of what I planned. These plans are legal documents for the most part so any deviations can result in all sorts of stuff nobody wants to deal with. From a fire suppression standpoint, I train and supervise 20 person hand crews and occasionally and engine and have travelled all over the country in all different types of terrain and fuel types and I have to have some critical observation skills to perform my job safely and make decisions that keep my people safe. So, I’m a lifelong student (Geek) when it comes to weather and topography. Trying to predict things is a super dynamic environment like a landscape on fire is having a constant head on a swivel and planning ten steps ahead. Recognizing features and conditions in this environment has translated really well into hunting for me.
Several years ago, when I joined the Beast I didn’t make the connection how my life long hunting pursuits and my professional knowledge had anything to do with one another. So, I see and read from this longhaired, big buck slaying, relentless Wildman named Infalt, there are all these factors that deer rely on for security and this is what you do to kill them. He’s dropping milk weed sitting on the leeward side of a ridge top explaining the thermal tunnel concept and a light bulb turned on. I’m sitting there saying to myself, I know this! I know about all of this, but I didn’t know how a buck used this stuff to his advantage. From that point on my thought process changes in ways that I had never considered when approaching deer hunting. Being able to answer a question like, “why would a buck bed here”? took on a whole new twist. I immediately started having buck exponentially more encounters once I learned how to adapt all the concepts to my area and focused on the ins and outs of bedding. I know a lot of this knowledge is known to experienced members here. I think what separates the killers from the ones who are struggling, or learning is the ability to quickly evaluate a scenario whether that’s from a sit that relied on pre-season scouting or going in blind. Having the ability to trust your experience and instincts that puts you in the right tree or right spot on the ground. Also, to recognize when something isn’t working out and taking a chance on moving. I laid out some general definitions and terms that are basic. They all roll into one another, and overall, the big picture is made up of whether or not anyone of the factors and variable with weather or topography can or should be considered. As a disclaimer “THERE ARE NO DEFINITIVES IN TRYING TO KILL A BIG BUCK”. But if you aren’t asking yourself the question, “Why didn’t that work out?” or, “Why did it work out”. You are doing yourself a disservice. So I hope this offers another piece to the puzzle. Also, there is a podcast in the works with Jeremy (SeesofCheese) with GOING FOR BROKE OUTDOORS. That will be a better opportunity to expand on some concepts and how you can use them.
Wind /Thermals list of terms definitions
We will start really simple
Wind Direction: Is the direction the wind is coming from. For example, a north wind is blowing from the north.

Types of winds-General, Local, slope winds, Valley winds, sea/land breezes, transport winds

General winds: Large scale winds caused by high- and low-pressure systems but generally influenced and modified in the lower atmosphere by terrain.

Local Winds: Winds which are generated over a comparatively small area by local terrain and weather. They differ from those which would be appropriate to the general pressure pattern.

Slope winds: Small scale convective winds that occur due to local heating and cooling of a natural incline of the ground. Upslope during the daytime when the ground is being heated while sun exposure is present on a particular aspect. Downslope winds occur in the evening when the surface begins to cool and cold air begins to sink into the lowest possible elevation.

Valley winds: this is related to slope winds. The up-valley winds begin later in the morning than the upslope winds and are a result of slightly larger scale convective process. As an inverse, down valley winds normally undergo a transition much as the downslope flow and begins a few hours after dark.
*the strength, duration, and transition period of wind on any slope is a function of its aspect. And the onset, strength, and duration of slope winds will differ on every aspect. So, tactics and stagy will be affected by this.


Transport Winds: Is a measure of the average rate of the horizontal transport of air within the mixing layer. An average wind direction (the direction from which the wind is blowing) is provided. If winds are light and variable, then it may be best to consider local drainage.
• Transport wind is something I rely on for smoke dispersion when I’m implementing prescribed fire. The reason I point this out is because in my experience I’ve found that when transport winds coming from a given direction are at or above 15 mph there is very little chance of a wind shift with the exception of a frontal passage.

Sea breeze: A breeze (wind) blowing inland from the sea generally during daytime hours. A result of differential heating of the water and land surfaces. Usually begin around mid morning on the east coast. They strengthen during the day and end around sunset. These can get very strong.

Land breeze: a breeze blowing to the see from inland during evening hours as a result from the differential cooling rates of the land and water surfaces.
*Cool going to warm
Aspect: Cardinal direction toward which a slope faces. Look at it in a skiers perspective. Exposure is a term that can be used for this as well.
Atmospheric stability: According to the American Meteorological Society, (also called static stability), the ability of the atmosphere at rest to become turbulent or laminar due to the effects of buoyancy. Air tending to become or remain turbulent is said to be statically unstable; one tending to become or remain laminar is statically stable; and one on the borderline between the two (which might remain laminar or turbulent depending on its history) is statically neutral.
Stable atmosphere: A condition of the atmosphere in which a parcel if displaced either up or down, will tend to return to its original level. Important thing to remember that vertical motion is restricted.
Unstable atmosphere: A condition of the atmosphere in which a parcel of air, if displaced either up or down, will tend to continue in the direction of displacement. Vertical motion is enhanced
-There will general assumptions in regard to stability and weather parameters and weather processes
-pressure
High pressure produces stable conditions through subsidence. Subsidence is the downward or sinking motion of air in the atmosphere. Subsiding air warms due to compression. Increasing temperature and decreasing humidity are present in subsiding air. Subsidence results in a stable atmosphere inhibiting dispersion.
Conversely, low pressure is usually associated with unstable air
-Lifting
Lifting an air mass layer will make it become more unstable. And lifting can happen as a result of convection, frontal passage or Orographic. (caused by an air mass running into mountains) Typically, air masses are stable far ahead of a front, unstable near the front, and stabilize behind the front.
-Winds
Sudden increases in winds can break up an inversion quickly and increase the instability of the airmass
After mixing actions by the winds, the lower levels could very well be unstable. However, the degree of instability would be less than the calm wind situation
-Temperature
Heating from below and/or cooling from above will increase instability, while cooling from below and/or heating from above will make the atmosphere more stable. So, hot sunny days result in high surface temperatures and thus make the lower levels of the atmosphere unstable. Clear, cool nights produce the opposite effects (inversions).
-Topography
Topography effects heating/cooling of slopes and valleys, and thus the stability. For example, south facing slopes are generally warmer and have greater instability above them than north facing slopes
Daily and seasonal Changes in stability occur. Normal daily changes in stability are related to temperature changes. For example a typical summer day with clear skies and light winds, the lowest layers of the atmosphere are stable at night(greatest stability just before sunrise) and unstable during the late morning and afternoon. The greatest instability is during the afternoon (hottest part of the day). Normal seasonal variations in stability are related to the seasonal variations in temperature. Winter has more stable conditions than the other seasons due to colder temperatures and longer nights. Stability changes frequently and those changes are directly related to surface temperature. The most unstable conditions are associated with the warmest surface temperatures and the atmosphere becomes more unstable as surface temperatures increase.

What is a thermal
A thermal column is a column of rising air in the lower altitudes of Earth's atmosphere, a form of atmospheric updraft. Thermals are created by the uneven heating of Earth's surface from solar radiation, and are an example of convection, specifically atmospheric convection.

Thermal Switch
I think we kind of mislabel this. If a thermal is a column of warm air rising it will no longer rise if something is affecting the influence of the sun heating the earths surface. As the earth rotates around the sun and the exposure to the sun of different aspects shift the thermal column will dissipate and the air will cool and start to sink to the lowest possible spot. So, the thermal just dissipates, causing the opposite (falling) reaction. But when you take things into consideration like differential heating and cooling of variable surfaces, mediums, and vegetative cover it effects the timing of the switch. Water has another unique effect on thermal activity. It takes much longer for standing or slow-moving water to change temperature. The time lag can be days, weeks or months. The difference between air and water temperature create a pulling effect of air, In our concern it affects scent control and in some cases it may be visible immeasurable. Whether it goes from water to land or from land to water can be a result of time of day, or temperature due to time of year or change in seasons.
Thermals and lack of topography, does flat land have thermals?
Yes! Its just a heated column of air. If you’ve ever sat an all-day sit on a fall day after leaf off with a high pressure blue bird day and dropped milkweed when the forest floor has full sun exposure you will see it rise straight up when there is little to no wind influence. Also, the more unstable the atmosphere the more lift will occur. Another great observation is watching turkey buzzards trying to get in a thermal. You will see them soaring in that circular pattern and gaining altitude.

Swirls due to topography/obstacles
Anytime wind encounters an obstacle it swirls. Water always makes for a great visual for showing examples of this. Eddies form when water passes a rock or a structure. It creates a wrapping effect where it often creates a current that comes back on itself or a rolling effect. We mostly encounter this on a horizontal plane in hunting situations. Great example is the thermal tunnel on the leeward side of hills. I see the horizontal rolling effect when you have difference in canopy heights especially when the wind direction coincides with a low canopy going to a higher canopy height. Gust will really manifest this. When revisiting some of the terms and definitions one thing that I stated was the earths surface creates friction and the environment never stays static other than the physical topography or obstruction. Being familiar with an area can be beneficial to managing conditions in a dynamic environment. But being aware of what may be possible when identifying certain features in an environment lets you anticipate shifts during critical hunting times. And keeping things like this in mind especially going in blind on that first sit can get you that much closer to getting a crack.

Thermals and Water
Which way do thermals go (cold to hot, hot to cold, land to water)?
Generally cooler air is going to move to warmer air when thermal input from the sun is a factor. The warmer air will rise and pull especially when thermal input from the sun is present or water is warmer than the ambient air temperature. Cooler air sinks and usually sinks to the lowest point in the terrain or the area that cools the quickest with lack of thermal input.
My experiences with water usually occur with early season hunts. Either hunting water sources, mostly small ponds. and often adjacent to marsh or swamp edges. Waiting for bucks to come out of isolated bedding and intercepting them where their trail exits the marsh into the timber.
The ponds I hunt are extremely small and, in most cases, when the sun goes down closer to prime time the wind will die down and ambient air temperature will begin to drop and the warm water of the pond will have a thermal rising and it will be stronger if there is an opening in the tree canopy. This usually overrides what was/is the predominant wind direction. These are the times that using milkweed is so telling. The milk weed will get sucked into direction of the pond which would be very concerning if you were worried about a deer approaching and catching your scent. But it will gently pull it then send it straight up into the thermal column. If air in water temperature is the same this isn’t going to happen and if the water is colder than the ambient air temperature your scent will drop into the water in light wind conditions.

I had bumped a buck on an entry route on a really warm day a several years ago early season accessing a spot to a hidden pond in the middle of a thinned pine stand via the train tracks running parallel to the stand. He was bedded on the downwind side of the stand not 15 yards off the tracks. He sat there and must have watched me forever until I walked practically on top of him until he busted out. He was a big bodied deer but he was plowing through thick chest high pine regeneration, so I didn’t get a really got look at his antlers. I sat that evening but knew I was probably hurting myself, but one plus is he didn’t get my wind. I waited a couple weeks to try it again, but I approached from a different direction. The wind the first time around was NNW and now it was NNE. It was enough of a shift maybe only 40 degrees in direction that I thought it would keep him in that same bed but keep me from being exposed. I got in clean and early and sat on the edge of pond hoping he would grab a drink before heading out to food. 20 minutes before the end of legal light I saw him approach from his bed and he walked in a big circle hooking down wind of the pond about 30 yards out. I thought I was going to get winded as he passed but he proceeded to bed down directly down wind of me. Wind to his back with heavy cover behind him and very alert scanning for anything that may have been approaching downwind of him. I dropped milk weed to figure out how that was occurring because there was a enough of a breeze for my scent to easily get to the buck, but the milkweed began to drop and pull toward the pond and once it reached the canopy opening it rose straight up. It was a good example of a thermal due to the higher temperature of the water in conjunction with the cooling air temperature.
I’ve run into a bunch of situation hunting near marsh and swamp edges that has forced me to focus on worst case scenario in terms of set ups and has made it critical in most cases to identify bedding post season because the sits usually have to be set up for “off winds”. There is usually some head scratching going on. Early season I know in the evening my scent is going to pull toward the bed either because there is enough water in the direction of the bedding that is going to have an evening thermal pulling the cooling air from the woods to the water. the marsh or swamp is the lowest spot and is dissipating heat faster than the woods and the cooing air is sinking and seeking out the lowest spot. Both scenarios favor the bedding. There has been a been several times where I’ve had some morning hunts trying to catch a target buck coming back to bedding in late season during leaf off, and it’s been over before it started. Relying on what the wind direction is forecasted for before the wind becomes a critical influence. I got set up extremely early and noticed that when it got light enough to expect movement my scent was pooling and drifting in the travel direction of a buck headed back to the bedding area. The colder air down in the swamp and stream bottom was dumping out once the air temperature was warmer than the water and once the sun came up began to heat the forest floor and the thermal pull had a greater influence than the intermittent breeze that started to become present once the sun rose. It took a significant amount of time for the predicted wind direction to become an influence.
Long story short. Where you encounter and how you encounter water can contribute to another factor managing thermals or when they dissipate and considering that in pre planning or picking spots that work out best for the given scenario.

Thermal hubs/Box Canyon
Part of this wind and weather discussion relies heavily on a pretty good understanding of topography. So, I would emphasize becoming proficient with map reading skills and learning what certain features look like on a topo map. What has been identified as a thermal hub is what I’ve come to know as a box canyon. Basically, a series of ridges making a bowl, mostly steep sided with one way in and one way out. This feature causes all sort of scenarios that are erratic in nature. They cause wind to swirl very erratically as a result of eddying effects. If the wind is aligned it cause updrafts. And the heating of the valley floor from the sun causes strong thermals and since there is no gaps or predominate saddles the air has a hard time escaping. The inverse is when that thermal falls due to lack of input from the sun mostly due to aspect and cooler air begins to all funnel down all sides of the hub to lower valley floor. As the cool air drops below the warm air there is enough turbulence to send your scent in any direction. I think you see so much sign in these spots because at any given time it gives a deer security because with all the air moving it favors their nose. The mornings are tough in these spots because unless the inversion starts to break up your scent is just going to hang and most likely heavily pool in or around your set. The relative humidity is going to be super high there in the morning. There will be dew laying in most cases during that time of the year. All things again that are good for keeping your scent cone intact.
So great spots for the deer and really difficult for the hunter. Staying to one end or the other I think could help your chance out the most out the most bc the opening end may not confine all the factors with wind and scent as much. And the back end is where the thermal lift will concentrate once the inversion starts to lift. But again, there are zero diminutives. Jut know going into the situation that its high risk which sometimes translates into high reward

How does Humidity affect scenting conditions?
I spent a lot of time with bird dogs. One in particular was a really good all-around purpose trained machine. when I thought about whatever we were perusing whether it was birds rabbits, sheds, or a dead buck, I always thought of it in terms of what kind of scent cone was being put out and how the general weather conditions and environment were going to affect what it was going to take for the dog to get a nose full of scent. And one of the things that always played a huge factor in that scent cone being more predominate was the relative humidity. Dry days with high pressure a fair amount of wind was always horrible. Basically, nothing for the scent molecules to bond to. So, it was the difference between the dog being able to lock on to whatever we were going after from a distance and having the ability to detect the faint odor and pinpointing her objective. Woodcock for a dog are great to get on. They stink. The ground scent holds for a long time under the right conditions so I would try and visualize what the dog was smelling and thought of myself as a big smelly woodcock in relation to a deer’s environment. And thought about my impact I have in a given are that I’m trying to get after a buck and why its easier to burn a spot up really easy in this regard because of your presence in a given are based on general weather conditions and the amount relative humidity in the air. A week of no rain, with a high-pressure system and dry vegetation. Its going to equate to lower relative humidity. A lot more thermal input from the sun with is going to have a positive influence on thermals forming and lifting your scent cone up and out and also helping to volatilize your scent cone and your ground scent isn’t going to be able to stick around as much. Heavy moisture laden air is putting you at more risk and having you to regard your scent control. Bucks based on how they bed in a lot of cases especially in areas where when a thermal dissipates and air dumps into a swamp or marsh a big buck is almost always set up to catch scent coming from the outside into his bed for this scenario because most times his eyes aren’t his best detection tool or even a factor. Humidity can play a big factor on exactly how strong your scent cone is.
So can of worms successfully opened?

[Uncle Lou]

Thank You for putting this together Erich. Just starting to read it now.

[Uncle Lou]

I just changed the title to better reflect the content, primarily for future searches. But I have no doubt this will end up in the all time Best BEAST threads.

Attention all BEASTs. This is what is properly called an instant classic. Can't wait for the pod cast. If I can absorb about 10% of this I feel it will make me a better hunter.

[Marshbuster89]

I’m all ears! I’ll be looking through this more after work

[moondoondude]

Great write-up, very relatable.

There was some terminology in regards to wind types, in particular, that i was unfamiliar with even though i had previously witnessed and/or understood the concept and/or science behind the concept.

If you do another write-up or continue offering, please provide more of your personal experiences. You do a great job offering a scientific explanation or analogy for whitetail behavior (dog and humidity example,wind lifting over water in an open canopy, etc.).

You have the knowledge to break down a set-up, and exactly what is happening scientifically, in order to play on a whitetail's instincts. That could help a lot of guys and maybe make a lightbulb go off.

[greenhorndave]

I just changed the title to better reflect the content, primarily for future searches. But I have no doubt this will end up in the all time Best BEAST threads.

Attention all BEASTs. This is what is properly called an instant classic. Can't wait for the pod cast. If I can absorb about 10% of this I feel it will make me a better hunter.

Yeah, this was amazing. Lots to chew on. (huge understatement)

Thanks to BB and Lou for tag teaming on this!

[PK_]

Dude I am such a wind geek. I absolutely love this topic.

Obviously with your profession you take it to another level. Incredible write up.

When you learn to make those water thermals work for you, you can really be untouchable.

The coolest thing about learning this stuff at an intimate level in a variety of terrains is that it translates to hunting just about any species, anywhere...