Can I walk onto a field and tell you which way the wind is blowing from? Most of the time. Can I step into a courtyard and do the same? It's much harder. Can I explain why the wind seems to change direction, gust, swirl, be stronger at my shoulders than at my ankles, or be moving in two different directions at the same time? At best, I can take a guess. Wind can have a major impact on your dog's efficiency and effectiveness in a search. How much do we really need to know about wind to have fun in K9 Nose Work? The answer, my friends, is - well, it's not an answer per se, just some ideas...
What is there to know about wind?
A lot. Just checking the Wikipedia entry for wind will introduce you to terms like Coriolis effect, geostrophic wind, gradient wind, and the Beaufort wind force scale - and that's just in the first few paragraphs. I won't go into any detail here, but according to the Wikipedia entry, wind is the result of several factors including the earth's rotation and the difference in absorption of solar energy between the equator and the poles.
Professional detection handlers - especially search and rescue (SAR) - need to know a lot about wind. They need to know how wind travels over different terrain, under different weather conditions, and at different times of the day and year. An excellent resource on wind and its effects on scent is SAR handler Hatch Graham. He's written a number of articles on the subject, some with illustrations and simple explanations of the complexities of searching in the wind. Take a look at "Convection Turbulence and the Airscenting Dog".
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| Illustrations from Hatch Graham's article, "Convection Turbulence and the Airscenting Dog" show how scent moves away from a source under different weather conditions. |
A classic book on scent work, Scent and the Scenting Dog by William Syrotuck, is an overall interesting read. I don't have an excerpt here (you'll have to buy the book), but Chapter 6, "Atmospheric Factors and Airborn Scent", discusses wind and its effects on scent.
Enjoy reading up on the effects of wind on scent, but realize that there is a huge difference between an academic understanding of what wind can do to scent, and applying that understanding to a search to affect your dog's probability of success in finding source odor.
How much do you, the K9 Nose Work handler, need to know about wind?
My mentor and friend, Penny Scott-Fox, CNWI & a founding instructor of K9 Nose Work is well above the average in her understanding of wind and how to read what it's doing in a search area. She's an accomplished sailor, so it's not a magical super power; she acquired her skill through experience reading and using the wind. I have sailed once - on a hobie cat - and have no such ability to use the wind to my advantage. A K9 Nose Work handler can get by with a layperson's understanding of wind (e.g., it's blowing in my face, therefore, I'm facing into the wind), but some search scenarios will be very challenging without a little above average skill.
In the first official NW1 trial the exterior search was set up to cover the area between the curb and the full length of a street-facing building. The hide was placed in the ground in the grassy median between the street and the sidewalk, directly in line with the building entrance. The wind was blowing strong that day and causing the scent to pool against the doors of the building. An understanding of how wind affects scent would have helped more than a few handlers move their dogs away from the doors and back into the wind to avoid a false alert and give them a better chance at sourcing the odor.
Many vehicle searches are made more difficult by wind. A dog and handler team can easily convince each other that source odor is present when it's really just scent from a vehicle blowing under another vehicle and collecting in it's wheel wells or on it's running board.
For most K9 Nose Work searches, as long as you give your dog an opportunity to search the entire area he will likely pick up scent and find the source odor, regardless of what you know about the wind. But, the less you know about the wind, the harder it will be to rule out pooling or blowing scent, or to know which direction might be the most productive for your dog to search. So, don't worry about taking college courses in wind studies, but do try to learn enough to give your dog the help he deserves in a search.
Using your dog to learn about wind
I can go search some storefronts for an odor hidden in a recessed doorway (or any little alcove) with my dog and know little else about the wind beyond the fact that it is blowing, and after our search I can put together a pretty good idea of what direction it was blowing from and what it was doing along the storefronts. If your dog picks up scent along the wall on his way to odor, the wind is blowing at you and you're heading upwind (into the wind). If your dog passes the odor and doubles back excitedly, the wind is likely coming from your back and you were heading downwind (with the wind). Once your dog gets into the alcove, if he traces the scent close to the source, then turns away and works in a circle, possibly even spinning around several times, then the wind is very likely spinning that same way - with help from your dog, you've identified an eddy current!
Parks are great places to learn about the wind with your dog. Find some picnic tables and see how the wind affects the way the odor travels by watching your dog work. If you place a hide at the end of a picnic table top and your dog is catching scent away from the table or on nearby objects and working his way - maybe air scenting - right back to the source, then the wind is very likely blowing from the opposite end of the table. If your dog chases scent along the table or picks it up at the opposite end and works the length of the table back to source, the wind is probably blowing the scent across the table.
Alleys are also fun to do searches in when the wind is blowing. Set a hide on one of the walls, a few feet off the ground - you can usually find a pipe or some object to attach an odor container to - and then do the search from both ends of the alley and note any differences in your dog's behavior. When you start with the wind in your face (upwind), your dog will be very actively working that scent blowing along the wall, bouncing up and down, chasing it with the wind. When you're working downwind toward the odor, your dog might cover ground quickly and pass the odor before showing really clear signs that he's on to something.
The wind isn't everything
As mentioned earlier, wind is just one factor affecting how scent moves and how your dog works that scent to its source. Temperature and terrain are two others. You, as a handler, are also a factor affecting how your dog works. Temperature can make scent rise and fall more dramatically. Terrain can cause scent to trap, or to travel an unexpected path. Handlers can do innumerable things - often unintentionally - to affect a dogs success in a search. While it's helpful to isolate each factor for discussion, none of these factors are completely independent in impacting the scent picture for your dog.
Temperature - A seemingly simple ground hide in a parking lot can become challenging when the asphalt is hot, but the air temperature is cooling. The scent rises straight up and disperses in a plume. The same effect can be seen in an interior corner hide on a chair where the room is very hot compared to the cooling temperature outdoors. The scent rises up and travels along the walls away from the corner making the hide hard to source unless the dog is able to get directly above the hide.
Terrain - A search where the ground is uneven, sloped, or varied in any way can affect scent in ways that are not intuitive to the human observer. An exterior search in a grassy area with trees where a ground hide is placed in a bowl shaped depression can result in scent that traps in the depression, and scent that escapes the depression in such a way that there are not direct trails of scent back to the source, rather, the scent trails are broken and varied. In this scenario, you may observe your dog searching and catching scent all over the search area - even in places far away from the source odor. Often, the only way for your dog to find the hide will be to cross over the depression in just the right way for your dog to catch the pooling scent that will lead him to source odor.
Handler - The scenting abilities of dogs are undeniable. When a dog fails to find source odor in a search, it's almost never because the dog can't smell the scent. A dog can detect scent in the 10's of parts per billion. There are many reasons why the dog might not find source odor, one of those reasons is inadequate access to productive areas. When working on leash, a dog is restricted by where the handler will allow him to go. An experienced handler knows to make sure his dog is searching the entire area in a search. This means observing when a dog has covered the area, but not really searched it. It also means knowing the difference between a dog productively working scent to its source, and a dog who appears to be working scent, but can't seem to source anything or make the decision to move on. The latter dog needs a little help to leave this confusing scent picture and start working the rest of the search area. He needs you. If you're unsuccessful searching the rest of the area, you can always come back to the part of the search area where your dog showed all the interest; a fresh look may give him just what he needs to sort things out and bring success for both of you.
This is still your dog's game
Have fun thinking about search areas in a whole new way, but don't let your own preconceptions - about how scent might travel and how your dog should work an area - get in the way of your dog's superior sniffer. No matter how much you learn and how much you think you might know, your dog is still the expert, using a sophisticated tool to solve a complex problem; and when he does need help, it will be your skills at observing your dog - not the wind - that will make you a valuable teammate in your searches.
Happy Sniffing!
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