Swamp / marsh thermals

[Autumn Ninja]

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.

To take this a step further....weather patterns like high pressur and low pressure systems will let you know how that swing will take place...clock wise...counterclock wise.

[addisonlee]

Great info here Dan.

[Stanley]

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.

To take this a step further....weather patterns like high pressur and low pressure systems will let you know how that swing will take place...clock wise...counterclock wise.

Good points Ninja. Not only do differences in air pressure help determine wind speed and direction, they help forecast precipitation and clear weather. High pressure indicates sinking air where clouds cannot form. Low pressure indicates rising air, which allows clouds to form, bringing rain or snow. Winds blow clockwise around an area of high pressure and counter-clockwise around low pressure. So in short on a clear day normally the wind will swing clockwise and on cloudy rainy days normally the wind will swing counter clock wise. When hunting season comes around I monitor the weather channel as often as I can. If I'm in remote areas with no cable or TV a weather channel radio is what I listen to.

[KLEMZ]

Here is a short read on land/water thermal breezes.
http://www.newton.dep.anl.gov/askasci/w ... a00249.htm

So basically they are saying if you were bowhunting very near the edge of a cool swamp, or large pond, or a lake, in otherwise flat terrain that you can expect an "onshore thermal" (away from the cooler water) during the warmest part of the afternoon. I would assume that as late afternoon/evening sets in the "offshore thermal" (towards the cooler water) would then kick in. Obviously, this would only work on a very calm day.

Does anyone have any experience that backs this up?
Dan, what time of the day did the bears smell the scent coming towards the swamp?

[dan]

Dan, what time of the day did the bears smell the scent coming towards the swamp?

Evening.
It don't have to be dead calm either... On the day the bear was using the thermal there was wind, but any time the wind stopped and it got calm ( even for just a couple minutes ) the thermal would change the air current direction. Its also noteworthy that I could not feel the thermal current at all. It just felt dead calm at that moment, but checking with milkweed, you could see it.

[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.

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.

Old age is a stinker.

[dan]

bump

[Singing Bridge]

The discussion so far has been about thermals "near" marsh / lake / swamp... how about deep within the interior of a marsh, which is different in structure from a heavily wooded "swamp"...

[Swampbuck]

The discussion so far has been about thermals "near" marsh / lake / swamp... how about deep within the interior of a marsh, which is different in structure from a heavily wooded "swamp"...

I was wondering that as well, in a flooded swamp or marsh where the water is all around. Would the thermals come into play at all? I would think not but??

Once again great thread!

[PK_]

If the water is warmer than the air it will push the air, if it is cooler than the air it will pull the air.

Does that make sense?

Think; hot water, steam rises.

[headgear]

Here is a short read on land/water thermal breezes.
http://www.newton.dep.anl.gov/askasci/w ... a00249.htm

So basically they are saying if you were bowhunting very near the edge of a cool swamp, or large pond, or a lake, in otherwise flat terrain that you can expect an "onshore thermal" (away from the cooler water) during the warmest part of the afternoon. I would assume that as late afternoon/evening sets in the "offshore thermal" (towards the cooler water) would then kick in. Obviously, this would only work on a very calm day.

Does anyone have any experience that backs this up?
Dan, what time of the day did the bears smell the scent coming towards the swamp?

I don't know that I have noticed a onshore mid-day thermal but if its calm that makes perfect sense, I will keep an eye out for it. Evening thermals to ponds or water I have witnessed a lot, use to get busted by them all the time before the beast.

[Swampbuck]

If the water is warmer than the air it will push the air, if it is cooler than the air it will pull the air.

Does that make sense?

Think; hot water, steam rises.

Right but in flooded flat land would it not tend to rise straight up, or move with the wind? I can see that on the edges of water it would move to or from and area because of the tempature differential, but in a uniform area it seems it would just rise or fall vertically or go with the wind. Seems flatland with no water or flooded flatland would be the same in this regard but i'm just guessing?

[dan]

If the water is warmer than the air it will push the air, if it is cooler than the air it will pull the air.

Does that make sense?

Think; hot water, steam rises.

Right but in flooded flat land would it not tend to rise straight up, or move with the wind? I can see that on the edges of water it would move to or from and area because of the tempature differential, but in a uniform area it seems it would just rise or fall vertically or go with the wind. Seems flatland with no water or flooded flatland would be the same in this regard but i'm just guessing?

Wind will trump thermals... Very light winds may cause swirling when thermals are pulled along the ground in a different direction than the actual wind... Warmer water or warmer ground than the air will cause rising thermal every where... A rising thermal will pull air (and scent) from surrounding cooler areas.

[PK_]

If the water is warmer than the air it will push the air, if it is cooler than the air it will pull the air.

Does that make sense?

Think; hot water, steam rises.

Right but in flooded flat land would it not tend to rise straight up, or move with the wind? I can see that on the edges of water it would move to or from and area because of the tempature differential, but in a uniform area it seems it would just rise or fall vertically or go with the wind. Seems flatland with no water or flooded flatland would be the same in this regard but i'm just guessing?

I find that in the interior of large cypress swamps the wind is dead calm, even if there is some wind that day. Thermals will rise to the tree tops and then follow the wind stream.

Along the edges of the body of water, thermals pull/push the air horizontally, if you are in the center of the body of water it moves them vertically. Think of it as a magnet. It will draw or push in ay direction.

[dan]

bump