Scent Cone Basics by Patriot K-9 Services 

                                          Explosives detection team Courtesy of Patriot K9 Services 

Scenting conditions that your dog must work in can vary greatly.  It will vary with the time of day, temperature, humidity, and wind. The hotter and drier it is, the more difficult it is for your dog to pick up on the scent cone.  The best conditions are moderate to cool temperatures with some humidity, warming conditions, and no wind (or a very light breeze depending on topography).  This situation can most often be expected to occur in the mornings.  The warming conditions will evaporate the humidity which takes the scent with it in an upward direction (no wind conditions) before flattening out relatively close to the ground.  In the evening the opposite will occur.  That is, the cooling will return the scent cone closer to the ground if warming air has caused it to be lifted. Remember! Hot air rises and cold air sinks carrying the scent cone with it each way.

With that in mind, the best times of the day for an air scent detecting dog are mornings and evenings with cooler temperatures, some humidity, and little or no wind.  On the other hand hot weather with no humidity, as you find in many parts of the Middle East for instance, or the deserts of the western United States, do not give the scent a chance to rise, move, and disperse as efficiently as it does in ideal weather conditions making hard work for a scent trained dog.

Whether a tracking dog, bird dog, drug dog, or explosive detection dogs , they are all at the mercy of the conditions they are being asked to work with.  The scent cone they are looking for does not always run parallel to the ground.  It can begin after leaving the source to rise vertically, especially on the hot days with no wind.  In that case the dog would have to be standing on top of whatever he’s trained to detect to give a positive indication.  It can settle in “pools” on the ground.  It can flow down a hill much like water.

So how can we use these facts to help our dog help us?  If possible, when working in hot conditions where you suspect the scent cone to be rising vertically, try to work the dog from above the suspected areas to be searched then continue your pattern to the lower area.  This would more often than not apply to outdoor searches than it would to vehicle or building searches.  Of course always enter the search from downwind when possible.  On very hot dry days slow your search pattern substantially to give your dog the best chance of picking up the scent cone.  If your K-9 has given a positive indication where there is obviously nothing there, try searching upwind with a criss cross pattern keeping in mind how scent cones move. Weather, obstacles, and air flow may have him thinking he is at the source when he’s not.  Remember, our dogs are great at what they do but they are not a magic bullet.  Our dogs are just one more tool we have at our disposal.  Use your head to help him use his nose.