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.
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