Lowbarometric pressure could cause your moisture laden scent to actually be pushed to the ground.

Todd could feel the heat rising that morning
It's a great scene, very honest

I have sat in stands and have never been winded morning or evening. I have some deer gets you and I have no idea how the deer got my scent. How the wind, thermals, terrain affect a stand location is beyond my knoowledge. Just try and keep the wind in my face and the deer in front of me. When one comes from beyond i cross my fingers[8D]

I agree with Jeff here .... seems easy to me ...

Thermals only come into play when its cold out. I usually refer to them as longhandles though!

So as a thermal rises it cools, the "thermal" air is mixed in with surrounding air. As more thermal rise that morning is your scent than getting pushed back down?

Again I don't know what happens to my scent as it leaves my location.

As the air warms, .....well, here....

A thermal column (or thermal) is a column of rising air in the lower altitudes of the Earth's atmosphere. Thermals are created by the uneven heating of the Earth's surface from solar radiation, and an example of convection. The Sun warms the ground, which in turn warms the air directly above it.
When a pool of warmer air accumulates, it expands and becomes lighter (less dense) than the surrounding air mass. The mass of lighter air will then rise, but as it does so it will cool due to expansion. This process will continue until at some height the pool of air will have cooled to the same temperature as the surrounding air, at this stage the air will stop rising. Also associated with a thermal is a downward flow surrounding the thermal column. The downward moving exterior is caused by colder air being displaced at the thermal top.
The size and strength of thermals are influenced greatly by the properties of the lower atmosphere (the troposphere). Generally, when the air is cold, bubbles of warm air formed by the ground heating the air above it, can rise like a hot air balloon. The air is then said to be unstable. If there is a warm layer of air higher up, an inversion can prevent thermals from rising high and the air is said to be stable.
Thermals on the Sun typically form hexagonal prisms (Bénard cells).
Thermals are often indicated by the presence of visible cumulus clouds. When a steady wind is present thermals and their respective cumulus clouds can align in rows oriented with wind direction. Cumulus clouds formed by the rising air in a thermal as it cools and ascends, until the water vapor in the air begins to condense into visible droplets. The condensing water releases latent heat energy allowing the air to rise higher. Very unstable air can rise to great heights condensing large quantities of water and so forming showers or even thunderstorms.
Thermals are one of the many sources of lift used by soaring birds and gliders to soar.
A similar phenomenon can be seen in a lava lamp.

I usually carry a baggy full of the white puffy seed things you get out of milk weed pods. It is amazing, even on days the wind seems "steady" or calm, to see where that thing ends up. When you think of the complication of the fluid dynamics of that air flowing through the trees, hills, etc it is beyond calculation, let alone me (a jackass) sitting in my stand and determining where my scent is actually being carried/dispursed. You can have a general idea, but specifics.... forget about it.

Where we hunt elk the thermals can really get the wind swirling in the morning. That swirling has cost me more chances at elk than I can even remember. They play a HUGE role in hunting mountainous terrain, and usually they play the role of the spoiler

Yes, and they should, particularly in hilly terrain stands.

I know when I was elk hunting, we chased them in the am and pm when strong thermals were present, midday the guide said it was pointless because the wind would swirl constantly and we'll only bump elk. The thermals in that mountain terrain were stronger than the wind present.

Jim:

Again (I'm not arguing your point....as it's not arguable) you're banking on an absolute "worst-case-scenario" that I'm comfortable throwing caution to the wind over. Some may not be. But like I said......if I stayed out of an area I KNOW is "hot" on an "iffy" morning........who gains the advantage? Me? The deer?

My '07 8 pointer was shot on Novemebr 6th. Wind was PERFECT. Temp was cool. Before daylight the wind shifted and the clouds rolled in (I thought I was gonna get wet). I stood my ground.....and killed him at 7:05......coming from (for maybe the first time in my life) EXACTLY where I thought he'd come from.

I was clean. It worked out. He's on my wall. He came from downwind of me (downwind at that time). I can't explain it other than to say......I thought it was gonna work out. It did. I only know that if I'd climbed down when the wind shifted.....he'd have lived another day.

I'm not saying "I" have the "killer instinct". But I'm saying "something" told me to trust my spot (I'd seen him in that area on the previous Friday, Saturday). I killed him Tuesday morning.

The best tool we have is between our ears. If yours tells you to get down every time the wind shifts.......by all means do so.

Jeff If I were hunting a herd of deer that numbered in the hundreds I too would worry little about a few winding me.

In my case I'm hunting a herd made up of less than 20 ,it takes few mistakes for them to know the game is on.

As I have six weeks to kill just one buck, the last two of those weeks being prime time. I pick the times that I chose to hunt, might be duck hunting might be deer hunting.[:-]