Aldeer.com Forums Alabama Deer Talk Serious Deer Talk Forum Hunting the thermals

Temp drop = thermals lowered
Temp rise = thermals raised

What, and how do, other variables affect thermal movement, i.e. hills, swamp, lowland, wind? Anybody have edumacated knowledge on this?

Slope orientation has more to do with it than anything else. Meaning how fast the ground warms. Southern facing slopes will warm faster allowing the air to flow up and hopefully out of the area.

Water will affect them a well. If you are hunting near water thermals will pull down towards it. I have found that milkweed is the best way to check them. There is a ton of information on thermals on the hunting beast website.

Other than the basics you stated, be mindful of steep inclines either from rocks or cedars. This can cause the air to swirl back on itself. Like an Eddie in a river. A light wind and thermals will work together. But heavy wind will push the thermal the direction of the wind. Don't get lazy and think that mornings = rising thermals. Really cold mornings with no wind will continue to sink. Humidity also makes air heavier. Use this cause bucks may be traveling on the bottom. I think the best thing to do is to keep a journal. Monitor temp and forcasted wind. Then write down actual scent direction at that stand and try to figure out why so you can learn more about all your other stands. Still learning myself, but I'm getting to where I like hunting mountains better than flat cause of thermals and hunting benches.

There has been a couple of good discussions on this subject last couple of years. They can be found in the archives if someone has time to do a search.

There's waaaay more to it than hot air rises and cold air sinks.

In the evening when you are up a tree look around and imagine pouring out thousands of gallons of water. Where will that water run to? That’s pretty much where your scent will go during low or no wind periods. Every plot we have is on a ridge top so we have to really be mindful of stand locations where the sinking air can be funneled where we want it to go and away from the major trails. Some of our bow stands are in weird locations where you have to climb a good bit higher because the tree is in a depression that will funnel the scent away from the field. Setting up right on the field or trail would funnel the scent right to the areas you would expect the deer to travel.

Thermals are trickier (to me) because they can swirl a good bit more, travel laterally across a ridge, etc. if you are sitting at the dead top of a ridge it’s usually not an issue but sitting on a bench or saddle you really have to pay attention to the topography. Mix in a swirling wind and sometimes it’s almost impossible to hunt a certain stand. For instance we have a ladder stand at the head of three different draws. The wind swirls in that spot almost all the time but on those real cold calm mornings (rare I know) you literally have the wind in your face in all directions as the thermals rise out of those draws.

Good information in this thread... will add a few things. First, the more severe the terrain, the more the downward thermals will be. As stated earlier, if there's water (creek/pond) in the low area the thermal will be stronger. Second, when the ground you're hunting around begins to warm, the thermals begin to rise. When the ground cools, the thermals begin to drop. I used to think mornings = thermals rising and evenings = thermals dropping. However, that's not technically true. Probably the first and last hour of every day thermals will drop (unless it's an overcast/day where temps are dropping dramatically)... and everything else will see them rise. I was hunting on a hill Saturday afternoon and about an hour prior to dark, the wind laid and that's when my scent began to be pushed down the hill (as opposed to across the hill). Third, deer in the hills travel according to the wind/thermals - they know how to utilize landforms to avoid human contact... so unless you're hunting deer from longer ranges, hunters in hilly land should learn about these things and apply them.

Bottom line there are so many variables to thermals in mountains that cause changes over fairly short period of time . Figure them out now and in a couple hours you may be hunting wrong. Lota guess work and luck involved.

Does the wind override the thermals today or the opposite? Is the humidity going to over ride the thermals? Is the sun gonna warm up quick enough so the thermals are working before the deer travel through to bed?

The only way I’ve found to hunt with a consistent wind is to hunt on top or the very top bench on a mtn. Once you start going lower the wind swirls non stop.The only exception would be a wind blowing perfectly parallel with the ridge or mtn.The worst case scenario is a wind blowing directly into the side your on in this case the wind just splatters in every direction. I believe older seek out areas with a consistent wind. I got a buddy that makes a good case for deer liking a variable wind were they can detect danger from any direction. I think variable scent makes them spooky not being able to pin point the danger. Hunting with a bad wind can educate a lot of deer real quick. Beating their nose is 90 percent of the game IMO.

I tend to agree with your friend about the variable wind. Bedding choices for mature bucks would tend to confirm that fact... they consistently bed with back to cover/wind and overlooking an open area.

Here is a really good podcast that I listened to earlier that goes into detail on thermals.

http://wiredtohunt.com/2018/10/18/ep-243-a-deer-hunters-guide-to-wind-and-thermals-with-ryan-furrer/

I would think a buck bedding in that situation is using a consistent wind.

Good post. Bout the only time you can get a consistent wind is on top of the plateau up here in the highlands . I get a kick out of the "just hunt the wind" boys, if it were only that easy. I like to find pinch points where they must alter their path and there's no way with the set up they can get down wind or down thermal either.

Yep. I try to get just a little more down wind of the does than the buck that’s scent checking them.My biggest problem is most of the deer are off the sides and not on top.

Thanks - Good info.

Its amazing what can alter scent travel, if you could predict it 100% of the time you'd be a millionaire. I'll check out the podcast and also see what infalt has to say on the hunting beast.

If he is still around this would be the guy to talk to. checkerfred, try to pm him, he did a interview on a podcast not long ago and explained it pretty good.

Went back and reread the post and realized I was in disagreement with his friend... I meant to say.

Infalt has some good info when it comes to winds and thermals.

Increased humidity DECREASES air density, i.e. makes it lighter. Use a psychrometric table or air properties calculator. For example, where I hunt, elevation is 300' above sea level. For 32 F and 40% RH, air density is 0.07974 lb/cu ft. If RH increases to 80%, density is 0.07966 lb/cu ft. Molecular weight of water is roughly 18 g/mol regardless of liquid or gas phase. Air without water is roughly 29 g/mol. More humidity = more water = reduced density for the overall mixture.

You guys is way more smarter than me.