Swamp / marsh thermals

[dan]

I don't think its been pointed out in detail yet, but there is some thermal activity on some flat land too that can have effects on your hunting and scent stream.
On flat land thermal effect is very minimal and hard to detect. I have seen people mislable it as deer haveing a six sense. When you are hunting near water ( swamp, river, lake, pond, bog, etc. ) if the water is cooler than the air it will pull the warmer air to it... Now if there is a breeze, any breeze, it should over ride this effect. But what I have noticed is that when hunting the edge of cooler swamps with the wind in my favor, right when it gets dead calm if I drop milkweed the milkweed will drift straight towards the cooler area.
On the day I shot my bear in Minnesota I was hunting the edge of a remote slashing 75 yards from a cool wet swamp. I set up so that my scent would blow over the slashing keeping bears from being able to circle effectivly. The wind was in my face, but every "dead calm" that occured pulled my scent stream towards the cool swamp in the oppisate direction. Twice I heard a bear move to where my scent stream was drifting with the thermal and scent check the pile.
Its amazing to me that the recognize when that scent stream changes directions and use that to there advantage...
Anywho, you don't hear much about this cause you are not going to see or feel this type of thermal with a string, powder, or other wind checking device. It takes a milkweed seed to see it. It will actually feel dead calm.
I know the 1st question will be "How far will this effect a hunter from the cool water"... I don't know the answer, but I think you have to be pretty close. That bear hunt was about the farthest I have seen and that was about 75 yards.

[adrenalin]

good obsevation, trying to hunting according to that might be tough though. If your hunting a point surounded by water and it's dead calm it could go any direction.

[dan]

good obsevation, trying to hunting according to that might be tough though. If your hunting a point surounded by water and it's dead calm it could go any direction.

Very true... But in some cases you can make adjustments. With the bear bait stand if I move the bait 10 yards I can shoot it from a tree in the slashing that will put the thermal current along the edge of the woods rather than in it where the bear could wind me.
On your point I am not sure if you could minipulate it or not... I think it may be possible to get on one edge and pull it a certain way.

[headgear]

Dan I have heard you mention this before and started paying attention to it. I hunt near some lakes and sure enough when things get super calm there is the slightest pull towards the cooler water.

I have also noticed bucks bed in swamps where they can use thermals from multiple directions coming off the higher ground in different directions. The elevation changes are not drastic so the pull isn't super strong but it is there and they use it any way they can.

[BCam]

This definitely explains a few encounters that left me baffled. Thanks for the post.... Great info.

[BigHunt]

This definitely explains a few encounters that left me baffled. Thanks for the post.... Great info.

X2

[dan]

bump

[straitnarrow]

Awesome info Dan your wind and thermal threads are very helpful.

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[DEERSLAYER]

I never gave this much thought before, but I wonder if the air is being "sucked" toward the water. I say this because as the air cools you can often see the steam coming up off the water. It seems this would cause a pull from the surrounding area.

[Buckfever]

I hunt this one bottom and from the direction of the prevailing wind theres a river and a huge rise in elevation almost like a bluff but it's just a substantial rise and I'm in this bowl portion of the bottom and the wind gets pulled back and up and then out of the bottom, unless it's a real strong south wind, there's almost no wind down there, you can just feel that up and back pull as long as I'm south of the draw I can hunt that almost any wind. 40 yards towards the draw and you're in the tumble effect and it gets pulled down the draw and over the bedding and you're wasting your time. Excellent point even when it's not hill country the contours and habitat can have a profound wind effect.

These are the fascinating things, that we expereince out there, it's like we're in a different world from everyone else.

[Stanley]

I have never liked calm days as the wind is never from any direction but shifts back and forth at least 90 degrees and usually more. If you are hunting a calm day and a slight breeze is from the west you can figure W NW and West SW at least. You also need to very careful of wind directional changes in the stand. If you are hunting a west wind that is going to change to a south wind. The wind just doesn't change directions but swings to that direction. You must be careful of where that wind swing takes your scent. You can't just hunt the wind as some suggest you must hunt where the wind is switching and swinging to.

[KLEMZ]

I live 5 miles from the west shore of lake michigan. there is a coal burning power plant in view of my house. I can look out my window and see the steam (I like to think its steam ) plume coming out of the 250 foot smoke stack, it is a great way to see the prevailing wind. BUT, there is also also a cooling tower that is only 30 feet tall that also spews steam. In the heat of summer, when the weather man says 5-10 mph west wind, the tall stack is indeed blowing towards the lake, BUT, the low tower is blowing JUST AS HARD away from the lake! So in other words, the first several miles of flat terrain west of the lake has a major thermal wind at ground level blowing the opposite way as the prevailing wind layer above it!

My understanding is hot land air passes over the cold lake, cools the air which sinks and gets squeezed out back towards land. I only see this on hot summer days, and mainly in the afternoon. I think the whole sinking air flow pattern builds momentum as the day warms up. Also, if the wind is higher than 10 mph I dont see this pattern. I think the prevailing wind over powers the thermal wind.

I'm not sure this has any impact on hunting (unless you hunt in the summer 5 miles from lake michigan). But it does demonstrate flat land thermals.

[Scot]

Very helpful information. Paying attention to these things is the difference between success and almost.

[jlh42581]

begs the question, is this why bucks travel the banks of rivers??? could very well be

[Autumn Ninja]

I never gave this much thought before, but I wonder if the air is being "sucked" toward the water. I say this because as the air cools you can often see the steam coming up off the water. It seems this would cause a pull from the surrounding area.

You and I had a long discusion on this a couple years ago...not (swamp/marsh thermals), but lake/river thermals and how the thermals will often fall all day long in some spots.