Air Flow

Adapted from NW120: Nosework Elements.  Taught by Stacy Barnett

Stacy’s Website:

Airflow and how it impacts hide placement and search results

Hide placement is EVERYTHING; it can make or break your search. Make the search too challenging and you have just over-faced your dog. Want an easy, motivating hide? Knowing a little about placement and airflow will make all the difference. Use this knowledge to plan an easy or challenging training session and also to understand why your dog searched the way he did.

When you place the hide in a location, it immediately begins to give off an odour. The longer it is in place the more odour collects around it. If you stood in the middle of the room while I placed a drop of perfume in the corner, initially you would not smell it but the longer you stood there, the better you could smell the perfume as the scent disperses through the air.

With little airflow, the scent disperses from the hide in a relatively symmetrical cloud. Airflow however will influence the direction of the cloud that is being dispersed. Other objects as well as surfaces in the area will also serve to collect the odour and prevent dispersal.

Think of scent dispersal as a color.  The scent closest to the hide is “red”. As the scent disperses from the source it becomes lighter and lighter red until it becomes pink and ultimately we can no longer see it. A highly experienced scent detection dog is very sensitive to the lighter “color” This is because he has a lot of experience and has honed his sensitivity to scent gradients. That light “color” really catches his attention and because he is very sensitive to scent gradients (skilled at going from “lighter” to “darker”) he can quickly work to the source of the odor. His foundation has taught him that it pays to be sensitive to that little bit of scent and to work hard to get to source. A less experienced dog will be less sensitive to the “lighter shade” and there will be a lot more wasted motion as he tries to work to the source.

Wind Direction and the Scent Cone

If you are standing with your dog and the wind is blowing directly toward you from the hide, your dog can work the cone of scent straight to the hide. The dog works the edges of the cone, some people call this “bracketing”. He moves his nose to the right and as the scent gets more diffuse he works back to the left. Sometimes he will actually move a long distance to the right and then the left as he moves forward. Other times it will seem as if he is moving in a straight line to the source.

If you are standing with a strong wind at your back as you start searching, you are going to go past the hide before scent reaches your dog’s nose and he will then work back towards source.

If the wind is coming perpendicularly to you, your dog will intersect the scent cone as he searches; causing your dog to turn and work to the source of the odor.

For the odours used in nosework, the primary influence on scent dispersal will be airflow. This is obviously a bigger factor outdoors but don’t underestimate the subtle but sometime difficult challenges it can have indoors as well.

Humidity and Scent

In addition to airflow, another consideration is humidity. When air is heavy and moist the scent will collect closer to the hide. With hot and dry conditions, the scent will often be lighter and disperse further from the source.

Using your understanding of airflow

  • If you want to build confidence and drive
    • Work downwind, with the scent blowing towards you.
  • If you want to build skill and problem solving skills or even stamina
    • Start upwind and work with the wind at your back, making it take longer until the dog gets into scent
    • Take advantage of obstacles and objects that will block or collect scent either nearby or a short distance away.

Use your understanding of air flow to control the difficulty of your search – challenge your dog but do not overdo it to the point where your dog starts to get frustrated or gives up. Like with all searches, if you find you have over-faced your dog then end the session and make the next search a better match for your dog’s skill set.

Additional Notes

  • Cold and moisture make air heavier and dense.
  • Warmth and lack of moisture make air rise up.
  • Use scent flow to control the difficulty or ease of your search.
  • Read about a dog’s olfactory system. There is lots of information out there. One article that will get you started is “Dog’s Dazzling Sense of Smell”
  • Odour flows in a “scent gradient” from the source of the odour away from it.
  • The primary structure that makes your dog such an outstanding scenting tool is the turbinates or rather their design. These are located within the nasal passages and contain olfactory receptors. Both humans and dogs possess a similar system of turbinates. However, in the dog, their design creates an exceptionally greater surface area for air to interact with the receptors. Obviously there are differences in nose structures within breeds of dogs – short nose breeds have much less area devoted to olfaction than their longer nosed cousins due to space in the nasal passage for turbinates.
  • The turbinates must be kept moist to work properly. This is really important. For dogs that are hectic as they work, panting, etc will need more breaks and hydration between searches to keep their nose in top sniffing form!
  • The mouth needs to be closed in order for air to flow through the nasal passages. When the dog is searching, you can tell when they find odour as they close their mouth and start working the scent cone!
  • Since airflow affects the direction of the scent cone, it’s very important to allow your dog to work every angle of your search area. Some examples:
    • A room with an open door. If the hide is near the door and the airflow is pushing it into the other room, the dog will be “upwind” and will have a hard time picking up the odour until they go through the door and back in.
    • A container near a wall. If the hide is placed on the side of the container nearest the wall, your dog may not pick up on the scent unless they search along the wall.

The most important point to remember:

There is only one expert when it comes to scent theory and dynamics and it isn’t you! The true expert about scent dynamics is your dog. Allow your dog to teach you what you need to know. Even more importantly, if you better understand scenting dynamics you are less likely to assume that the dog is wrong when things do not go as planned.

Additional Resources

  1. This is oriented towards search & rescue air scenting dogs however it is excellent reading on understanding how airflow works:
  2. WEBINAR:Introduction to Scent Theory for Nosework.
  3. NW150: Scent Theory and Dynamics.
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