Hunting the Falling Thermal

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d_rek
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Re: Hunting the Falling Thermal

Unread postby d_rek » Tue Oct 30, 2018 1:34 pm

Divergent wrote:
d_rek wrote:Observed interesting thermal tunnel from dropping thermals a few days ago on a riverbottom hunt. Hunted a large oxbow with good bedding. The oxbow itself is the lowest elevation point with a ridgeline along the norther half of the oxbow and along the S side with a 60-70ft elevation change that ultimately converges to a draw up to the mainland on the SW side of the oxbow. Wind was steady out of the N at 5-10mph walking in. When we got to the top of the north facing ridge, on the south side of the oxbow, the wind was still in our face blowing back onto the mainland. When we descended the ridge and we felt wind hitting us in the back of the head. We moved about 100 yards away from the bottom of the ridge and the wind was back in our face, though occasionally blowing back at us. I believe this was a 'thermal tunnel' from the shaded N facing ridge and N wind direction. As the N wind hit the shaded ridge which was cooler than the rest of the surrounding topography the cooling thermal kept the air current swirling at the bottom of the ridge rather than rising up and over the ridgeline.

As I moved closer to the ridge on the N side of the oxbow I observed air current taking milkweed off to the NE along the bottom of the northern ridge. I believe as the N wind air current traveled over the northern hilltop with a south facing slope the air was also being affected by falling thermals and rather than the air stay high the thermals were pulling the air toward the ground and causing the current to swirl along the bottom of the S facing ridge, though why it was travelling NE is still a mystery. Maybe it was being pulled toward the river? Not sure. There was a spot in between both the N and S ridges where wind was blowing N as it was on the mainland.

Were we setup right for the thermal effect? I'm not sure. Probably would have been better to be right on the water for that hunt so that the falling thermal would have went over the water and not swirled around on land. Still a very informative lesson on thermals.


There’s a lot going on in this one. It might be easier to decipher if I saw the topography.


PM sent.


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Voz
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Re: Hunting the Falling Thermal

Unread postby Voz » Tue Oct 30, 2018 4:13 pm

Does anybody have any examples on thermals in the morning in “low spots in ag fields” in flat farm country?

Also, do you guys pay attention to the barometric pressure when considering thermals in the morning/evening?
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NYBackcountry
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Re: Hunting the Falling Thermal

Unread postby NYBackcountry » Wed Oct 31, 2018 1:41 am

Voz wrote:Does anybody have any examples on thermals in the morning in “low spots in ag fields” in flat farm country?

Also, do you guys pay attention to the barometric pressure when considering thermals in the morning/evening?



No examples on the first question, sorry.

As far a pressure and thermals, I've been paying attention to that a lot lately. Not enough info to give you my thoughts yet but check out the Wired to Hunt podcast Ep.243 with Ryan Furrer of the QDMA. He was heavily influenced by the Wensels and offered some really interesting observations on pressure, wind speed, temperature, and thermals and how they all interact and influence one another. He provided some awesome observations that are not talked about as often.
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Divergent
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Re: Hunting the Falling Thermal

Unread postby Divergent » Fri Nov 02, 2018 5:15 pm

d_rek wrote:
Divergent wrote:
d_rek wrote:Observed interesting thermal tunnel from dropping thermals a few days ago on a riverbottom hunt. Hunted a large oxbow with good bedding. The oxbow itself is the lowest elevation point with a ridgeline along the norther half of the oxbow and along the S side with a 60-70ft elevation change that ultimately converges to a draw up to the mainland on the SW side of the oxbow. Wind was steady out of the N at 5-10mph walking in. When we got to the top of the north facing ridge, on the south side of the oxbow, the wind was still in our face blowing back onto the mainland. When we descended the ridge and we felt wind hitting us in the back of the head. We moved about 100 yards away from the bottom of the ridge and the wind was back in our face, though occasionally blowing back at us. I believe this was a 'thermal tunnel' from the shaded N facing ridge and N wind direction. As the N wind hit the shaded ridge which was cooler than the rest of the surrounding topography the cooling thermal kept the air current swirling at the bottom of the ridge rather than rising up and over the ridgeline.

As I moved closer to the ridge on the N side of the oxbow I observed air current taking milkweed off to the NE along the bottom of the northern ridge. I believe as the N wind air current traveled over the northern hilltop with a south facing slope the air was also being affected by falling thermals and rather than the air stay high the thermals were pulling the air toward the ground and causing the current to swirl along the bottom of the S facing ridge, though why it was travelling NE is still a mystery. Maybe it was being pulled toward the river? Not sure. There was a spot in between both the N and S ridges where wind was blowing N as it was on the mainland.

Were we setup right for the thermal effect? I'm not sure. Probably would have been better to be right on the water for that hunt so that the falling thermal would have went over the water and not swirled around on land. Still a very informative lesson on thermals.


There’s a lot going on in this one. It might be easier to decipher if I saw the topography.


PM sent.


In the photo you sent me I’d expect you to have some inconsistencies that would be difficult to setup on. You have a couple of draws that meet up in that one area in red. I’ve found that if you move from one side of a draw to another then you might be able to find the right combination to setup on. A lower wind speed or a west/southwest wind might be your best option if you’re hunting close to that area in red. Your wind and thermals should flow in the same direction on a west/southwest wind and be your most consistent option. You could also hunt your more consistent north wind in the bottom and close the gap after your falling thermals override the wind in late evening.
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Divergent
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Re: Hunting the Falling Thermal

Unread postby Divergent » Fri Nov 02, 2018 5:33 pm

Voz wrote:Does anybody have any examples on thermals in the morning in “low spots in ag fields” in flat farm country?

Also, do you guys pay attention to the barometric pressure when considering thermals in the morning/evening?


Personally, I would try to stay away from ag fields during the morning, but if you hunted it in the morning before the ground heats up then you’d setup in a low spot below a deer trail that funnels up into the low spot. This way your falling thermal and scent is carried away from where they might approach. I normally find them heading back to bedding in the morning, so I would setup on a creek crossing(lower elevation than the crossing) between the field and bedding.

As far as pressure, I typically find that the lower pressure coincides with higher humidity and cloud cover. The heaviness in the air and the shade from the clouds tend to keep your thermals lower to the ground. It’s the exact opposite during sunny, high pressure days.
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Re: Hunting the Falling Thermal

Unread postby funderburk » Sat Jun 08, 2019 10:55 pm

This is an incredible thread. Thanks for all the charts, divergent. Super helpful to see it laid out like that.
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Re: Hunting the Falling Thermal

Unread postby Divergent » Sun Jun 09, 2019 2:05 am

funderburk wrote:This is an incredible thread. Thanks for all the charts, divergent. Super helpful to see it laid out like that.

Thanks funderburk!
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Re: Hunting the Falling Thermal

Unread postby greenhorndave » Sun Jun 09, 2019 4:15 am

funderburk wrote:This is an incredible thread. Thanks for all the charts, divergent. Super helpful to see it laid out like that.

Agreed. This one's a gold mine.
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Re: Hunting the Falling Thermal

Unread postby funderburk » Sun Jun 09, 2019 4:35 am

Divergent wrote:Sun is starting to set to the west. The first bit of shade is cast on the east facing slope. The thermals start to drop. The west facing slope is still in the sun. The thermals are still rising. Image


This is great. So, the draws have more thermal activity, rising or falling, than the slope of the hill? Just like water would react?
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Re: Hunting the Falling Thermal

Unread postby Bowhuntercoop » Sun Jun 09, 2019 12:35 pm

funderburk wrote:
Divergent wrote:Sun is starting to set to the west. The first bit of shade is cast on the east facing slope. The thermals start to drop. The west facing slope is still in the sun. The thermals are still rising. Image


This is great. So, the draws have more thermal activity, rising or falling, than the slope of the hill? Just like water would react?


Depends on the steepness of the terrain and also the time of the year with the foliage left on the trees. Thermals will also flow with the direction of water which can help or hurt you.
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Re: Hunting the Falling Thermal

Unread postby Divergent » Mon Jun 10, 2019 10:41 am

funderburk wrote:
Divergent wrote:Sun is starting to set to the west. The first bit of shade is cast on the east facing slope. The thermals start to drop. The west facing slope is still in the sun. The thermals are still rising. Image


This is great. So, the draws have more thermal activity, rising or falling, than the slope of the hill? Just like water would react?


In this specific situation, the hillside with the falling thermal is caused by the sun setting in the west which caused the east facing slope to reach shade sooner and cool quicker. The west facing slope is still in sun and the rising thermal.

Like the comment above, there are a lot of factors. Ambient air temp, foliage, water, wind speed, and height of the ridges to name a few.


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