Hunting 101: Part 4 – Understanding Wind & Thermals

By Johnny Mack

Being a successful hunter requires a lot of grit, patience, knowledge and a little bit of luck.  One of the ways to build your own luck, is to understand how and why wind and thermals play an important role in the success of your hunt. Luck is often confused with preparation and experience. In part 4 of our Hunting 101 series we are going to cover and explain the importance of wind and thermals while hunting. Applying this information while out in the field will not only help you but also explain why things did not go as planned .

Back to the basics

Before diving all the way in, you need to have an understanding of the natural flow of heat energy. Heat will always flow from hot to cold. This is why you can warm someone up through body heat if you make contact with them when they are cold. Also why a cold beverage becomes room temperature when exposed to the hot air it contacts.

Nature is constantly working on balancing itself to an equilibrium. And the reason why your scent is constantly being carried away from you when you are hunting. Knowing how energy flows should be a guiding factor in how you go about pursuing animals.

Scent is carried by either the wind or what hunters refer to as thermals. Wind is the perceivable natural movement of air. Why thermals can be both seen and unseen. A useful way hunters view thermals, is through spraying chalk into the air. This is commonly referred to as “windicator.” The chalk is light enough to be moved by the unseen air flows and allows hunters to see which way their scent is being carried. Carrying windicator is extremely useful when hunting and recommended, but not necessary.

  • Windicator stashed in bino bivy for quick access
  • Example of windicator

Thermals & rules of thumb

Now that you have an understanding how heat flows, it’s time to talk rules of thumb. Knowing that heat rises and flows from hot to cold, we can now dive into how thermals are consistent. One rule of thumb is to hunt high in the morning and low in the evenings. Simply put, thermals will go up in the morning and down in the evening carrying your scent as they move. As the sun rises in the morning, it heats the highest points of elevation first pulling the thermals upward. If you are planning a stalk of an animal you are going to want to keep this in mind.

Using the rule of thumb that thermals flow uphill in the morning and downhill in the evening, use the elevation lines to get an understanding of how your scent will be carried.

When out in the field, it is imperative to always keep your scent from traveling to where you are expecting animals to be or come from. Animal’s sense of smell is their number one defense against predators. One of the biggest things that can ruin a hunt is blowing out animals because they smelled you before you even had an opportunity to see them. This is why hunters will refer to keeping the wind in your face as a top priority.

Animals use sight, sound and smell to detect predators.
Prey animals will predominately travel the wind. Allowing them to see what they can’t smell and smell what they can’t see. Which way is the wind blowing in this picture?

Although keeping the wind in your face is important, there are some variables to remember.

  1. Scent travels in a line. If the animal is not in the path of the scent trail, it will not smell you.
  2. Wind flows like a river. Topography affects the travel path and will cause scent to bend or turn.
  3. When calling animals to you, they will try and circle downwind in order to smell your scent. Keep this in mind when an animal is on the move or when looking for them if you are hunting from a stationary location.
  4. Rain can act as scent control. As precipitation passes through the air, it bumps into scent particles pulling them to the ground and diluting them.
  5. Moving water such as creeks or rivers will create their own air flow in the direction that that water is traveling.
  6. Making a play on an animal might not be possible because a change in thermals. Be patient and know what time of day it is. Mid-morning & mid-afternoon/evening thermals will switch.
Wind will move with the terrain. Think of valleys, canyons and draws as wind tunnels. Using the map above, how would you imagine the thermals would flow?
Valleys can act as wind tunnels.
Moving water will create its own air flow pulling scents with it.

shifting & swirling

As the earth rotates causing the sun to shine from different angles, shadows will be cast causing the ground to change temperatures. As shadows move with the daylight, thermals will move as well. Thermals are consistent based off of the sunrise and sunset and switch directions once the sun is completely out. Causing thermals to constantly shift as they move from hot to cold. In the hunting world this is known as swirling. When you are in thick timber, wind has a tendency to swirl more than normal.

The sun is rising from the east. What way are the thermals moving?
Shadows from the sun can cause thermals to shift throughout the day.

To help you understand how the thermals and wind will flow where you are hunting, look at topographical maps. The direction the sun rises and sets in correlation of the elevation and terrain features can give you a pretty good idea of how you would want to enter, setup or hunt a particular piece of land.

Combining how and where to find animals along with your knowledge of thermals and air flow, will drastically increase your opportunity at finding animals and potentially creating a shot opportunity. Remember to constantly check where your scent is going while on your pursuit. Be patient, move slow, and keep the wind in your face.

In the morning as thermals are moving uphill, glass from above.

If you have any questions, want to know more, or have topic ideas feel free to email us by using the contact link from the menu or direct message us on Instagram @washington_backcountry.  Thanks for reading.  For more helpful tips and insight, be sure to check out our This is How I Hunt series as well as our Hunting 101 series on YouTube (Link).

Leave a Reply