(Hypothetical) Ridge Thermal

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Zee
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(Hypothetical) Ridge Thermal

Unread postby Zee » Sun Apr 22, 2018 10:02 am

Long time follower, first time posting (since it’s been so long I forgot my old username). Hypothetical question. Say you have a ridge that runs straight W to E. Assume there is no wind from any direction, so the air movement is totally driven by thermals. Also assume there are no knobs, fingers, ditches that come off this ridge. Since the S facing slope is getting warmed by the sun, the thermals would be pulling from the bottom to the top on that side. But what would be happening on the N facing slope?

Since the air is rising on top the ridge due to the S facing slope, would air from the N facing slope also be drawn to the top of that ridge to fill the void?

As the sun drops, will the thermals begin to drop from top of the ridge to bottom of the ridge on each side? Assuming the N facing slope would begin to drop sooner than the S facing slope?


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Divergent
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Re: (Hypothetical) Ridge Thermal

Unread postby Divergent » Sun Apr 22, 2018 11:17 am

I would assume the void is being filled by air from the valley and not necessarily the north side. I use a tactic in a similar situation, but involves two north to south ridges or secondary points and early morning east facing slopes and late evening west facing slopes. A west facing slope will still have rising thermals and you can drop down to a creek crossing crossing and interesect a deer dropping down across the creek from the east facing slope. The east facing slope cools sooner.

What’s your reasoning for asking? Access?
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Re: (Hypothetical) Ridge Thermal

Unread postby Zee » Mon Apr 23, 2018 12:02 am

Access, yes. But the main reason is trying to figure out WHY I find 90% of beds (buck and does) on the N facing slope...cover is the same, topo is the same, food the same. Predominant winds are N and W, so I always assumed the S facing slope would be more advantageous. Big woods scenario in northern Wi, so I would also think the S facing slope would be better for late season bedding. But year after year scouting shows me they prefer the N facing slope...and that’s what I can’t figure out...
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Re: (Hypothetical) Ridge Thermal

Unread postby rfickes87 » Mon Apr 23, 2018 1:04 am

Are you positive about the cover being the same? 100%? We can't smell like a deer so sometime they can confuse our logic. Is it at all possible the wind/thermals offer a better advantage to the deer on the north side because the bedding is more secure there because its at the exact elevation of the ridge that the deer prefer? Perhaps on the south side the wind isn't doing exactly what the deer want where the cover is. Deer can be extremely particlur about choosing the right areas for bedding. Areas that are very thick and offer great cover might not have any bedding because they can't use the wind to there advantage like they can somewhere else. I've seen this first hand and then walk out thru an open area and find a huge bed right on a crest of a hill that is wide open.
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Re: (Hypothetical) Ridge Thermal

Unread postby Jeff G » Mon Apr 23, 2018 1:51 am

Are you talking about deer or big bucks? Two different animals. The big bucks will set up on the points or micro points on the hillside. wind blows over their back when they bed there.

Does can be on the wind blown side, they do not take the wind into account as much as the big bucks do when bedding.

Maybe you are seeing more Doe sign on the opposite hillside.
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Re: (Hypothetical) Ridge Thermal

Unread postby Divergent » Mon Apr 23, 2018 11:58 am

Some ridges might only be used under those south winds or only during summer because they’re typically cooler. I would be interested in whether or not the hair is old or if you really have to dig down deep into the leaves to find hair. If your hair is fresh and on top it could be a killer setup on that particular wind because they may prefer bedding there under certain conditions. I would keep looking, but focus on overlooked spots on the south facing ridge or find another ridge in close proximity. They may prefer another ridge for N/NW wind bedding. All ridges are def not created equal.
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Re: (Hypothetical) Ridge Thermal

Unread postby Zee » Tue Apr 24, 2018 9:47 am

How do I post a picture in my response? I have a drawing that depicts this hypothetical scenario.

Is the cover truly 100% the same on both sides = no. It is mainly a ridge of hardwoods, but I would say that each side, over the length of the ridge (which is ~0.5 miles) has the same number and type of thick areas on either side of the ridge (N facing or S facing). I would say maybe 5 areas per side of the ridge, each <10 acres.

I just re-walked this entire area again this weekend, with snow still on the ground, and there is hair in the beds - so I would say it's fresh.

As I mentioned in my first post, I see the majority of bedding (now that's saying BOTH buck and doe bedding) is on the N facing side. I do find way more doe beds, in general, than the beds that I would call buck beds. I would say I find 10-20 doe beds (maybe more), per bed I would say meets to criteria to be a buck bed.

Assuming all variables are the same (including ZERO wind, so the only air movement is driven by thermals), how does the air move on the N facing side of the ridge when the S facing side is being warmed by the sun?
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Re: (Hypothetical) Ridge Thermal

Unread postby Divergent » Tue Apr 24, 2018 10:39 am

Zee wrote:How do I post a picture in my response? I have a drawing that depicts this hypothetical scenario.

Is the cover truly 100% the same on both sides = no. It is mainly a ridge of hardwoods, but I would say that each side, over the length of the ridge (which is ~0.5 miles) has the same number and type of thick areas on either side of the ridge (N facing or S facing). I would say maybe 5 areas per side of the ridge, each <10 acres.

I just re-walked this entire area again this weekend, with snow still on the ground, and there is hair in the beds - so I would say it's fresh.

As I mentioned in my first post, I see the majority of bedding (now that's saying BOTH buck and doe bedding) is on the N facing side. I do find way more doe beds, in general, than the beds that I would call buck beds. I would say I find 10-20 doe beds (maybe more), per bed I would say meets to criteria to be a buck bed.

Assuming all variables are the same (including ZERO wind, so the only air movement is driven by thermals), how does the air move on the N facing side of the ridge when the S facing side is being warmed by the sun?


I don’t know why there would only be bedding on the north side. It would make more sense for a deer to be bedded on a south facing slope.

Take some milkweed to find out what the wind and thermals are doing.
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Re: (Hypothetical) Ridge Thermal

Unread postby brancher147 » Tue Apr 24, 2018 11:02 am

Zee wrote:How do I post a picture in my response? I have a drawing that depicts this hypothetical scenario.

Is the cover truly 100% the same on both sides = no. It is mainly a ridge of hardwoods, but I would say that each side, over the length of the ridge (which is ~0.5 miles) has the same number and type of thick areas on either side of the ridge (N facing or S facing). I would say maybe 5 areas per side of the ridge, each <10 acres.

I just re-walked this entire area again this weekend, with snow still on the ground, and there is hair in the beds - so I would say it's fresh.

As I mentioned in my first post, I see the majority of bedding (now that's saying BOTH buck and doe bedding) is on the N facing side. I do find way more doe beds, in general, than the beds that I would call buck beds. I would say I find 10-20 doe beds (maybe more), per bed I would say meets to criteria to be a buck bed.

Assuming all variables are the same (including ZERO wind, so the only air movement is driven by thermals), how does the air move on the N facing side of the ridge when the S facing side is being warmed by the sun?


I post pics using postimages.org. Just copy the hotlink for forums and paste into a message here.

I see similar bedding on some ridges, on the windward side with a northerly aspect much more than the southern aspect. Especially if there is a creek or river below. Take some milkweed with you and try to hunt it and you will see why they bed there.

And the thermals on the north facing side are not affected by the thermals on the south facing side. You just have to see what the milkweed tells you, as there can be some variability based on terrain.
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Re: (Hypothetical) Ridge Thermal

Unread postby elk yinzer » Tue Apr 24, 2018 11:29 pm

Some pure North facing aspects the thermals will pull down all day. In your hypothetical case it depends on the slope and the total amplitude of the mountain, but that is likely, with some air mixing at the top. If there is truly no wind there will probably be a cold sink at the bottom of the cold side of the mountain too. The deer get that smell uphill/see downhill effect the deer love to bed in the mountains. I see that with elk too all the time where they'll bed in the dark timber of a North slope then cross over the ridge onto the South to feed. Also note that in interpreting sign, it is going to appear more abundant when it comes to seeing sign in the dirt and leaf litter, like trails and beds, than it really is on the moister North slope vs. the dry South aspect.
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