Thermals vs Wind

[gameflogger]

Thermals are hard to predict, often times the only way I can hunt some mountain or hilly areas is when it is dead calm and cold early in the morning when the air current is still traveling downhill and can be predicted, or with a screaming north wind that is continuous. It is so hard not to hunt an area that you know will be good. I may wait weeks until the conditions are right just for one morning hunt on a good area. Or you can try to bathe in fermented goat urine, shave all of your body hair and double up on the “earth scent enemas” the morning of.

 

[swampdonkey]

I prefer to plan> observe> adjust if need be. But with a pre conceived plan I can usually be where I assumed I could be before I even go there. Knowing the difference between prevailing patterns and thermal patterns saves me from disturbing stands only to find out (after tossing floaters) that I should have been somewhere else.
It's what I mean when I refer to being a planner as opposed to an observer. Gotta know why the wind is doing what it does.

Fair enough, i plan but not to that level i look at the wind app thing on my phone and go from there.

 

[woodsdog2]

I personally believe that its a combination of the leeward effect and thermals, not one of the other, because on most larger hills, the Bernoulli principle drive air more on the upper half. While this does create a vacuum to some extent, there is still usually a thermal rise coming from entire hill in our area at least.

Absolutely!!

 

[neonomad]

The farm I grew up on is above a river valley, about 100’ deep, and thermals are maybe the most important variable of the hunt, they will ruin any hunt if not careful. We have a lot of good bottom land with deer bedding there, but winds are so swirly in the bottoms it’s almost impossible to hunt em. And if you plan ambushes up top, the valley starts sucking in the evenings, often moving air right at the deer you’re hoping to set up on. In this diagram I set up along some egyptian wheat east of a food plot with a 10mph west wind; deer had been getting to this food plot in daylight. But early evening, any time the wind slowed down, that creek headed into the valley would start sucking air right across the food plot, and that creek is probably 90 yards from my blind site. I need steady 10mph winds here to have a shot. I could diagram at least 20 different crazy thermal situations just on this 75 acres. Edit: don’t even get me started on that really nice transition slope to the north, on paper it should hunt great but it’s a thermal nightmare too.

 

[Mschmeiske]

I don’t have as much experience as some, but I’d put my faith in thermals below 10 mph... as we approach 15mph+ I might have to reconsider...

 

[CooterBrown]

Hey Catman, I like your youtube videos.

What has helped me is imagining the landscape is a huge stream bed and the air moving is water. I can picture it better that way and anticipate things. I believe the equations and such for water and air flowing are very similar.

What is his youtube channel? I just received my @Allegheny Tom pods yesterday so I cant wait to seeeee what the wind is doing on my next hunt.

 

[CooterBrown]

Is there like a wind/thermals/turbulence class I can take somewhere because I've got lots to learn about this topic.

 

[Allegheny Tom]

Is there like a wind/thermals/turbulence class I can take somewhere because I've got lots to learn about this topic.

Ya gotta live and learn.
And in some terrain it's a lot easier than in other terrain.
You are on the right track with milkweed use, but don't
just watch it float away...observe, learn and apply to future hunts.
Im on a (north) leeward slope right now, but we have a sw prevailing wind around 10mph. Surface wind at my tree is actually moving opposite of the prevailing wind with a very nice up draft as shown by the milkweed. Nice situation.


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[CooterBrown]

Ya gotta live and learn.
And in some terrain it's a lot easier than in other terrain.
You are on the right track with milkweed use, but don't
just watch it float away...observe, learn and apply to future hunts.
Im on a (north) leeward slope right now, but we have a sw prevailing wind around 10mph. Surface wind at my tree is actually moving opposite of the prevailing wind with a very nice up draft as shown by the milkweed. Nice situation.


Sent from my SM-G970U using Tapatalk

Is it because of the updraft from the south wind coming over the top of the ridge kinda like a vortex( sand blaster)?

 

[Allegheny Tom]

Is it because of the updraft from the south wind coming over the top of the ridge kinda like a vortex( sand blaster)?

Yep. Exactly right.
20 years ago this type of pattern drove me nuts until I learned what caused it.
Now I realize that the "wrong" prevailing wind can actually create the perfect surface wind.

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[CooterBrown]

Yep. Exactly right.
20 years ago this type of pattern drove me nuts until I learned what caused it.
Now I realize that the "wrong" prevailing wind can actually create the perfect surface wind.

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So how far down the leeward side does this happen. 50 yards, 100yards. I'm assuming it also has to do with wind speed coming across the top of the ridge

 

[raisins]

Is there like a wind/thermals/turbulence class I can take somewhere because I've got lots to learn about this topic.

Best thing I did was drop milk weed all the time and then take note of what it was doing based upon time of day, terrain, wind direction, and speed. It helps a lot to have ONX (or similar) on while doing this and then figure out why the wind is doing what it is. The water in a stream analogy is useful because you can see water current a lot better and most of us have been staring at water flowing since we were kids so we have an intuitive sense of that.

You asked about Catman also.

Catman Outdoors

Home-brewed videos of real, fair-chase hunting, fishing, foraging, do-it-yourself projects, and other outdoor related videos.

www.youtube.com

 

[Allegheny Tom]

So how far down the leeward side does this happen. 50 yards, 100yards. I'm assuming it also has to do with wind speed coming across the top of the ridge

Yeah, that can be the hard part. Wind speed, angle that it hits the ridge, shape of the slope, breaks in the cover all effect the behavior of a wind eddy. Some days the eddy will be consistent and other days it can constantly swirl.
Similar to an eddy in a stream. Different flow rates will cause a particular eddy to behave differently with changes in volume. I learned a lot about wind behavior by paddling whitewater.

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[raisins]

So how far down the leeward side does this happen. 50 yards, 100yards. I'm assuming it also has to do with wind speed coming across the top of the ridge

I'd start thinking of it in terms of distance along the ground but also vertical drop.

I've had some different experiences. I find that on moderate sized hills that sometimes the entire leeward side has the turbulent backdraft and even some of the valley at its base. For instance, I hunt a smallish plateau with a 60 yards wide valley at its base. The wind direction on the top of the plateau is often exactly backward the direction in that valley/field. In fact, the wind being wrong in that valley is a good sign when I am walking in because it always reverses up top. On a bigger mountain, I don't think the "suction" has enough energy to move the larger amounts of air involved.

 

[CooterBrown]

Best thing I did was drop milk weed all the time and then take note of what it was doing based upon time of day, terrain, wind direction, and speed. It helps a lot to have ONX (or similar) on while doing this and then figure out why the wind is doing what it is. The water in a stream analogy is useful because you can see water current a lot better and most of us have been staring at water flowing since we were kids so we have an intuitive sense of that.

You asked about Catman also.

Catman Outdoors

Home-brewed videos of real, fair-chase hunting, fishing, foraging, do-it-yourself projects, and other outdoor related videos.

www.youtube.com

Thanks