Understanding wind and thermals in the mountains

[greg728]

I’ll be honest and come clean, I don’t understand that stuff either and don’t pay any attention to it I was just breaking his chops because people on here are always talking about balloons and all they (balloons) do is piss me off because I hate seeing trash in the woods!

There’s definitely something to it from what I’ve seen although I haven’t successfully hunted one. I make notes of balloons but when I find them I pick them up because I also don’t like trash in the woods and I don’t want anyone else to hone in on it lol.

 

[Topdog]

There’s definitely something to it from what I’ve seen although I haven’t successfully hunted one. I make notes of balloons but when I find them I pick them up because I also don’t like trash in the woods and I don’t want anyone else to hone in on it lol.

I shot a PA mountain buck this year while he was getting out of his bed at 30 yards, it was a thick nasty hole like none other, no balloon was spotted and I’m not sure which way the wind was blowing but my ears were ringing bad afterwards!!!!

 

[JoyRyd]

Thermals may be simple in NW CO but I havent seen it play out that way in the San Juan's. The only thing that is a 100% down there is air movement will generally follow the normal thermal pattern until you are in or close to in range of elk. Then regardless of anything else it will shift and blow directly to the elk. They could be upwind with a steady 15 mph breeze and that crap will do a 180 as soon as you start thinking about a shot.

Isn’t that what all the scent lok stuff is about?……Forget the wind and just hunt!

On a serious note: you do bring up a good point. It is safe to say that most big game animals are much easier to hunt while they are on the move. You don’t hunt a big whitetail buck in his bed very successfully. Do you? You are always better to hunt them while they are heading somewhere…..food or bed. Same with the elk. If you are running around the woods tooting a bugle or cow call chasing after them…in a spot that they are setup to use the wind…..of course you’re going to get busted.

Full disclosure: I have hunted the same private property for over 40 yrs. I do have an advantage of knowing the wind directions and which way the thermals flow at different times. I’ve learned the hard way, for certain.

I can’t help you in the San Juans. Their elk must be smarter than ours!

 

[raisins]

People get thermals and Bernoulli effect mixed up sometimes (Dan Infalt used to at least).

Thermals are a lesser effect, but they are also good to understand.

Here's Bernoulli effect in a nutshell. Let's say you have just a ridge line (simpler situation). The ridge runs north-south.

Let's say a wind is coming from the west. The wind will be more predictable on the west side of the rise (windward side) because the wind climbs the hill like a skateboard ramp. The leeward (east side) there is a suction and the wind at many points on the ridge will travel the reverse and be east to west. It is due to the wind over the ridge creating an area of lower pressure. It is similar to a wave curling over. When the wind doesn't hit at a perpendicular to a ridge but an angle, then it causes a rolling effect where the return wind on the leeward side is more perpendicular than the wind on the windward side.

If the wind is travelling from the north on this north to south ridge, it will be more predictable because it does not do what I described on the leeward side.

To understand it all better, I would check dominant wind direction for the day in the area and then walk around with a topo map and just drop milkweed all the time and watch it. I then envisioned the wind like water flowing and the hills and mountains like rocks in the bottom of a stream influencing the water.

You eventually get some intuition for new areas and a more thorough understanding of specific spots you hunt. I have places where if I look at the weather, then I usually know what the wind will be doing but am still wrong sometimes. And of course, my single ridge example is a huge oversimplification.

Also, the strength of the wind has an effect. The stronger the wind the more the Bernoulli effect (meteorologist or something might call it another name, but it does this based upon Bernoulli's principle).

With wind predictions, I also look for changing wind directions and changing wind speeds. Variable wind speeds tend to cause less predictable wind patterns and more changes in wind direction.

Thermals modify wind movement, but I have not seen them to be the primary factor to worry about except when the wind is very still. On a moderately windy day in the mountains, I forget to even think about thermals because the wind direction seems to overpower the thermals to a large degree.

 

[woodsdog2]

And now the real question… was a balloon there as well?

There was! I’m not joking, albeit about 30 yards to the east but on the same terrain contour!!!!! I was like….. are you kidding me right now?!?

 

[Allegheny Tom]

People get thermals and Bernoulli effect mixed up sometimes (Dan Infalt used to at least).

Thermals are a lesser effect, but they are also good to understand.

Here's Bernoulli effect in a nutshell. Let's say you have just a ridge line (simpler situation). The ridge runs north-south.

Let's say a wind is coming from the west. The wind will be more predictable on the west side of the rise (windward side) because the wind climbs the hill like a skateboard ramp. The leeward (east side) there is a suction and the wind at many points on the ridge will travel the reverse and be east to west. It is due to the wind over the ridge creating an area of lower pressure. It is similar to a wave curling over. When the wind doesn't hit at a perpendicular to a ridge but an angle, then it causes a rolling effect where the return wind on the leeward side is more perpendicular than the wind on the windward side.

If the wind is travelling from the north on this north to south ridge, it will be more predictable because it does not do what I described on the leeward side.

To understand it all better, I would check dominant wind direction for the day in the area and then walk around with a topo map and just drop milkweed all the time and watch it. I then envisioned the wind like water flowing and the hills and mountains like rocks in the bottom of a stream influencing the water.

You eventually get some intuition for new areas and a more thorough understanding of specific spots you hunt. I have places where if I look at the weather, then I usually know what the wind will be doing but am still wrong sometimes. And of course, my single ridge example is a huge oversimplification.

Also, the strength of the wind has an effect. The stronger the wind the more the Bernoulli effect (meteorologist or something might call it another name, but it does this based upon Bernoulli's principle).

With wind predictions, I also look for changing wind directions and changing wind speeds. Variable wind speeds tend to cause less predictable wind patterns and more changes in wind direction.

Thermals modify wind movement, but I have not seen them to be the primary factor to worry about except when the wind is very still. On a moderately windy day in the mountains, I forget to even think about thermals because the wind direction seems to overpower the thermals to a large degree.

"Bernoulli effect"
I've always referred to that as a "wind eddy". I had no idea that there was a technical name for it.

 

[woodsdog2]

"Bernoulli effect"
I've always referred to that as a "wind eddy". I had no idea that there was a technical name for it.

This is why I’m still wondering if that’s why the buck was bedded that way I talked about earlier. I have pictures of him facing back, looking up toward the ridge line from below….. he was facing north on a northwind over a steep bank of the ridge line. The only problem with classifying it as bedding due to the Bernoulli effect though is the north side of the ridge is very gradual and not steep at all so the “climb” of the wind like a skateboard ramp isn’t physically possible. Perhaps the steep south side of the same ridge, as strong winds pass over it from the north cause the same effect.

 

[woodsdog2]

Thermals are a lesser effect, but they are also good to understand.

Thermals modify wind movement, but I have not seen them to be the primary factor to worry about except when the wind is very still. On a moderately windy day in the mountains, I forget to even think about thermals because the wind direction seems to overpower the thermals to a large degree.

I’m finding that these deer in the “hollers” are completely out of the main wind so thermals tend to still command the scent stream and I want it pulling down to water or something. Plus, the wind never stays at robust levels it ebbs and flows and always seems to die right down at or around first light and last light when the pesky horned hill goats seem to want to bust me out the most!!!

 

[Allegheny Tom]

This is why I’m still wondering if that’s why the buck was bedded that way I talked about earlier. I have pictures of him facing back, looking up toward the ridge line from below….. he was facing north on a northwind over a steep bank of the ridge line. The only problem with classifying it as bedding due to the Bernoulli effect though is the north side of the ridge is very gradual and not steep at all so the “climb” of the wind like a skateboard ramp isn’t physically possible. Perhaps the steep south side of the same ridge, as strong winds pass over it from the north cause the same effect.

Call it the Bernoulli effect, or a wind eddy, or a reversal, or whatever, there is a seam where that wind pattern meets the predominant wind. Depending on several factors, the "seam" can be very well defined or highly variable and it can change from hour to hour or minute to minute. The extent of the variability is hard to predict. I'd venture to say the wind where your buck was bedded was not what you thought it was. There's a good chance that he was bedded along one of those seams.

 

[Bigterp]

Some great points! Have you guys that are consistently killing mature bucks found the need to have an airtight wind strategy? I’m saying my last 3 bucks I setup with wind that was going to get me busted, but gambling on shot opportunity before he hit my scent stream (thermal or wind direction ) ….. I think it’s a consideration but maybe not top of the least like I hear it discussed. I think scouting & being in the right spot related to your ambush & cover are as if not more important.

 

[davidallenjoy]

Some great points! Have you guys that are consistently killing mature bucks found the need to have an airtight wind strategy? I’m saying my last 3 bucks I setup with wind that was going to get me busted, but gambling on shot opportunity before he hit my scent stream (thermal or wind direction ) ….. I think it’s a consideration but maybe not top of the least like I hear it discussed. I think scouting & being in the right spot related to your ambush & cover are as if not more important.

Sounds to me like you were setting up on a just off wind, not a flat wrong wind. Just off is the choice we all need to be making most the time. A great wind for us seldom gets us where we need to be. A flat wrong wind, though, and you’re never even in the game.


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[raisins]

"Bernoulli effect"
I've always referred to that as a "wind eddy". I had no idea that there was a technical name for it.

Bernoulli effect is a general physics term to describe how when fast fluid goes over slow fluid that it creates a pressure differential (useful here, in airplane design, and the flow of water in pipes and much more). I used this term for lack of something specific to wind but there's probably a term for it that I just haven't heard.

 

[Allegheny Tom]

Some great points! Have you guys that are consistently killing mature bucks found the need to have an airtight wind strategy? I’m saying my last 3 bucks I setup with wind that was going to get me busted, but gambling on shot opportunity before he hit my scent stream (thermal or wind direction ) ….. I think it’s a consideration but maybe not top of the least like I hear it discussed. I think scouting & being in the right spot related to your ambush & cover are as if not more important.

There is no such thing as "an air tight wind strategy" in hilly terrain. There are behavior "trends" that helps us formulate plans but calling it an air tight strategy is delusion. Try to stack as many odds in your favor as much as possible. I really like when I find some sort of terrain feature or other obstruction that force deer to put themselves in a less favorable position.
Like @davidallenjoy said in post #31, Just off wind is a great situation. Barry Wensel likes to describe it as "almost wrong for him and almost right for the deer". It lulls them into a false sense of security. But those spots/conditions are not easy to find. This is when meticulous odor reduction practices can pay off. We have deer approaching just along the edge of our scent stream and it only take a wind shift of just a few degrees to blow-up the encounter. We aren't talking about deer getting a full nose of our odor, they are just on the edge of winding us. Being clean can make a difference. Wind versus odor practices...it doesn't have to be one or the other. Play them both.

 

[bigmike23]

Call it the Bernoulli effect, or a wind eddy, or a reversal, or whatever, there is a seam where that wind pattern meets the predominant wind. Depending on several factors, the "seam" can be very well defined or highly variable and it can change from hour to hour or minute to minute. The extent of the variability is hard to predict. I'd venture to say the wind where your buck was bedded was not what you thought it was. There's a good chance that he was bedded along one of those seams.

Where that seam is consistently gets the most pictures of great bucks in daylight. Where it also is is virtually unhuntable. There is no predicting it. It's a crapshoot. Everytime I've ever hunted it I got busted. I try to hunt the edges of it where you might get away with it

 

[raisins]

Where that seam is consistently gets the most pictures of great bucks in daylight. Where it also is is virtually unhuntable. There is no predicting it. It's a crapshoot. Everytime I've ever hunted it I got busted. I try to hunt the edges of it where you might get away with it

If you are right uphill from it, often times the milkweed often takes an upward trajectory and it's like you can't be smelled. Or go downhill and hunt uphill and your wind is being pulled strongly away from it. Right in it, I've experienced the same as you and you're basically in a washing machine that churns. To add insult to injury, near this area, what the milkweed does at ground level is very different from what it does when 25 feet up a tree. That's why I find not overhunting an area within a season, but returning to the same spot a few times each season allows me to predict a lot better.

 

[raisins]

There is no such thing as "an air tight wind strategy" in hilly terrain. There are behavior "trends" that helps us formulate plans but calling it an air tight strategy is delusion. Try to stack as many odds in your favor as much as possible. I really like when I find some sort of terrain feature or other obstruction that force deer to put themselves in a less favorable position.
Like @davidallenjoy said in post #31, Just off wind is a great situation. Barry Wensel likes to describe it as "almost wrong for him and almost right for the deer". It lulls them into a false sense of security. But those spots/conditions are not easy to find. This is when meticulous odor reduction practices can pay off. We have deer approaching just along the edge of our scent stream and it only take a wind shift of just a few degrees to blow-up the encounter. We aren't talking about deer getting a full nose of our odor, they are just on the edge of winding us. Being clean can make a difference. Wind versus odor practices...it doesn't have to be one or the other. Play them both.

Yep, and I try to be flexible as far as if the wind is bad, just leave and relocate or go home. It's hard to do though once you've setup and really want to hunt that day. Also, having a lot of areas, so if you think your wind swirled and busted you most likely, you can go somewhere else and let that spot cool down for at least a week (and 2 weeks seems a lot better).

I have a spot I love where I killed my biggest buck to date. It's usually unhuntable (and that's why bigger bucks are there) but with a certain wind it becomes really good. Fortunately, it seems no one else has taken the time to figure this out (on public).

The other thing I keep in mind is that bucks don't always travel with the wind in their face. They often will move if the danger area as far as wind is concerned can be scanned by them visually and the area where they could be crept up to from is blowing scent to them, similar to how they often pick bedding spots (looking down into the open with the wind hitting their back).

Hunting to me is turning into 3D wind chess.

 

[raisins]

Sounds to me like you were setting up on a just off wind, not a flat wrong wind. Just off is the choice we all need to be making most the time. A great wind for us seldom gets us where we need to be. A flat wrong wind, though, and you’re never even in the game.


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Time of year matters also. During peak movement during the rut, of course a buck will not walk straight into your scent, but if they want to go check on some does, then they will move to that area often without trying to be strategic in how the wind hits their bodies. More than once I have missed opportunities on bucks during the rut because I was thinking they'd move like they would pre-rut. For instance, I do not see mature bucks cruising old logging roads on hillside benches if it puts them more in the open unless it is the rut and doe trails cut that logging road and now it becomes a very handy doe-trail-checking cruising area. All of this is what keeps it fun for me. If it was easy I guess I'd be bored by now and have another hobby.

Of course, also during the rut, you need to take as another data point how the bucks will move so that the wind from does blows to them as well.

 

[raisins]

Some great points! Have you guys that are consistently killing mature bucks found the need to have an airtight wind strategy? I’m saying my last 3 bucks I setup with wind that was going to get me busted, but gambling on shot opportunity before he hit my scent stream (thermal or wind direction ) ….. I think it’s a consideration but maybe not top of the least like I hear it discussed. I think scouting & being in the right spot related to your ambush & cover are as if not more important.

I've done this when I don't have another better option and I'm willing to ruin the general area for the time being (like not come back in 2 weeks). If a spot is a honey hole and I know I can get a better wind later, then I won't risk blowing it out usually. That's why the saddle and being totally mobile is so great.

 

[raisins]

I’m finding that these deer in the “hollers” are completely out of the main wind so thermals tend to still command the scent stream and I want it pulling down to water or something. Plus, the wind never stays at robust levels it ebbs and flows and always seems to die right down at or around first light and last light when the pesky horned hill goats seem to want to bust me out the most!!!

I find in the hollows, that the dominant wind zipping over it and creating low pressure areas is still stronger than thermals. Maybe we are just calling thermals different things though. I'm calling thermals the result of local differential hitting (since the main wind is also a thermal when viewed at a global level). If I'm in a valley and the wind is whipping over the ridge lines that created the valley, then it's just swirling usually for me based upon that overhead wind. The local thermals though are influencing it but I'm seeing that drowned out a lot. On really calm wind days though, the local thermals can be money and highly predictable based upon time of day.

 

[bigmike23]

If I was invisible and made zero noise id bet with every dollar to my name id find a giant sitting in that mess every year. And I throw a cam in there and get pics all season long of great bucks. You can't hunt it. Not even the edges. The wind swirls and swirls. It's magical