Thermals

[rspecht55]

Could someone speak to thermals when hunting elk or any game animals in CO or WY. Hoping to learn a little more about when those change and what to look out for.

Thanks!


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[*zap*]

hot air rises, cold air drops....intense sunlight warms the ground fastest, usually 1/3 down from max elevation on the leeward side of a slope the rising thermal will meet the wind coasting over the slope and cause a vortex where scent from above and below can be checked. Not sure about elk but deer use the thermals more than the wind direction, especially when on home turf.

 

[hibernation]

Yep, that's pretty much it. Sun heats up hills and the warmer air generally moves uphill, sun goes down and cooler air starts to slide back down the hills. Transition times can be swirly.

There's some more to it, but that's the broad strokes. Count on it going down the mountain at dawn, and then by mid to late morning the uphill thermals should take over. They'll reverse again before dusk. It's less pronounced on cloudy or overcast days, and can even be influenced by localized terrain features. Finger ridges with shadier, cooler north slopes vs sunny exposed south slopes can have contrasting thermals at the same time of day. Cool river drainages and creekbeds can also draw air downhill even during the heat of the day.

 

[cnelk]

I did some research a few years ago about thermals.

Thermals should not be confused with Wind.
Thermals are driven mostly by the heating/cooling of the earth surface

Thermals are very gentle movements of the air, sometimes almost imperceptible.
Cold air sinking below the rising thermal causes a downdraft.
That\'s why you can feel thermals in your face in one spot, then feel it on your neck in another.

Typically the thermals move DOWNSLOPE in the mornings until the air heats. When the air heats up, it mixes.
After the air heats up and stabilizes, the thermals will be UPSLOPE during the day.
Later in the day, as the air starts to cool, the thermals will mix again and then just before dark, they will be predominately DOWNSLOPE again

Thermals are weather dependent. You wont have any consistent thermals if a weather front is moving thru.

Slope direction definitely has an impact. The sun or prevailing wind will warm one side or mix it before the other.

Here\'s some more info regarding thermals...
Downslope wind—

1. A wind directed down a slope, often used to describe winds produced by processes larger in scale than the slope. Because this flow produces subsidence, downslope winds experience warming, drying, increasing stability, and clearing if clouds are present.

2. Flow directed down a mountain slope and driven by cooling at the earth\'s surface: a component of the mountain–valley or mountain–plains wind systems; same as katabatic wind.

The many synonyms for downslope flow are sometimes used interchangeably, and this gives rise to ambiguity and confusion. Downslope can be used generically to denote any wind flow blowing down a slope, or it is used specifically for katabatic flows on any scale, such as the nocturnal slope-wind component of mountain–valley wind systems or mountain–plains wind systems.

 

[cnelk]

Now if you’re more of a visual person, make a fist and the knuckles are mtns and the fingers are ridges. In between the fingers are valleys


Thermals are like water and will follow down the same path - from the mtn tops, down the ridges and flow over into the valleys - like your fist.

 

[Huntnnw]

Hunting steep country with deep canyons that are forested adds another issue... you might be sitting up on that hillside with thermals blowing up in your face and you hear a bull below down in the bottom. You think wind is in my face and you begin to make your way closer, but as you near bottom the wind is blowing downhill! Many places I hunt the very bottoms the wind almost never blows up in September its a constant downhill with the creek

 

[insanelupus]

When hunting thermal country, remember, as a general rule, you are often better off approaching the animal on the same elevation/ level rather than above or below where you are at the mercy of thermals moving up and down the mountain.

 

[Scoot]

In one place we hunted in WY the thermals would swirl in the morning, swirl throughout the day, and swirl in the evening. It made getting in bow range more than difficult.

 

[Beendare]

In one place we hunted in WY the thermals would swirl in the morning, swirl throughout the day, and swirl in the evening. It made getting in bow range more than difficult.

.

 

[LostArra]

. No coincidence the animals like it .

.

Bingo^^^

Swirling thermals are one reason I "like" the prevailing winds in Wyoming. Thankfully calm days are rare.

Interestingly, I have a whitetail stand location that is just the opposite. I can sit there in any wind and rarely get scent busted. I think my scent must go straight up due to trees and terrain.