When you place a hide in a container, the scented cotton swab is the location of “source”. Source is the highest concentration of scent, and we want the dog to find its precise location.
When there is no wind or air flow, scent disperses outwards equally, in all directions. The pictures show scent spreading out in approximately a cone shape. In these pictures, brighter green represents stronger odor and lighter green represents weaker odor.
The longer you leave the scent (known as ageing aka soak time), the more widely the scent disperses into the environment. While the scent cone changes over time, an experienced dog has no trouble with ageing. Once his nose encounters the scent cone, he follows the path back to source.
AIRFLOW & WIND
While visualising scent plumes is helpful for human understanding, it’s actually a simplification of the complex, changing environments dogs encounter in real life. In most search environments, there is wind, or at least smaller air currents. Wind and air currents move scent around, messing up the tidy cone shape of the scent plume shown in the picture. Accordingly, current scent detection research more accurately describes the precise pattern of scent as a scent plume, but both terms continue widespread usage. We will use the terms interchangeably.
Outdoors, wind gusts may cause chaotic, erratic, unpredictable changes to the path scent travels, including swirling in circles and even changing or reversing direction mid-search! Scent is a moving target, and no two searches are identical.
Falling back on the foremost human sense of vision, envision smoke exiting a smokestack to be carried by the wind, eventually cooling and falling slowly to the ground at a distance from the chimney. Or picture how smoke from a bonfire dances upward in unpredictable shapes, dropping ash some distance from the fire when it’s windy. Those shapes are closer to how your dog “sees” scent patterns with his amazing nose, as he figures out complex puzzles.
Don’t worry: when you’re just starting to learn nosework in the lab, indoors, you can usually just follow your dog as he finds source. But if you want to know more about how wind affects nosework and how best to help your dog get to productive areas in more complex searches with wind, keep reading.
- For more detailed scent detection terminology, see our blog on Scent Detection Terms.
- Canine Olfaction Science and Law, Advances in Forensic Science, Medicine, Conservation, and Environmental Remediation, Ed. T. Jezierski et al, Taylor & Francis Group, Boca Raton, USA, 2016.