How Scent and Airflow Works

How Scent and Airflow Works

By Jennifer Pennington


How do those dogs find missing people?

This article was orginally published on the Hound and Found Blog:

Remember PigPen from Charlie Brown? He always appeared to have clouds of dust coming off of him wherever he went. This is not far from the truth.

Skin Rafts 

You have thousands of tiny pieces of your body leaving you every minute; 40,000 pieces to be exact. These tiny cornflake-like bits are called rafts 

skin rafts

They are made up of skin cells, hygiene products, bacteria, fungus, parasites, sweat, hormones, and enzymes. They are unique to each individual human. Even skin rafts from identical twins are different. Dogs can smell these rafts, and distinguish between different people.

Some skin rafts are lighter, and easily carried by air currents. Others are heavier than air, alighting on vegetation or falling to the ground.

scent theory smoke bomb


Dog Handlers pay attention to air currents. Skin rafts are carried along currents of air like millions of fluffy dandelion seeds. We also pay attention to physics. A great tool for visualization is smoke.

→ In the image to the right, the origin of the smoke is higher on the hill, and the smoke is falling.

Warm Air rises and  Cool Air sinks

Cold and moisture make air heavier and dense. Warmth and lack of moisture make air rise up like bubbles on a summer day. Your skin rafts first leave your body travelling upwards at 2mph along an air current your 98.6 degree Farenheit body produces. 

Without any air movement

Scent difuses evenly. 



But, of course, there is always something making air move.


Factors that affect Air Movement: Scent Threory

In idealistic theory: scent moves predictably like this:

Laminar Air Flow 

Laminar Air: straight flow of air, without ahy interference.



Turbulent Air Flow 

Turbulent Air Flow: laminar air hits an obstacle that creates chaotic behavior, which causes handlers and their canines to mutter choice words under their breaths.




Normal Daytime Air

When the ground heats up during the day time, air begins to rise.

 daytime air flow


Normal Nighttime Air



Coning Plumes

A dog will run perpendicular to the flow of the scent crossing in and out of the scent cone zeroing in to its source.

 coning air movement


Fumigating Scent

 fumigating air


Lofting Scent



Fanning Plumes 

 fanning plumes of air


Pooling Scent

 scent pool image


Eddying Scent

 eddying air current


Looping Plumes



Chimney Effect






The Dog is only Part of the Team

You are the brains. Your dog is the nose.

A search dog team will prefer to search into the wind, often zigzagging into the wind on small areas. A canine team can also perform searches along parallel sweeps perpendicular to the wind in larger areas. Remember to search ridges when air is likely to be rising and down in drainages when air is likely to be falling.


scent theory_smoke1 Time of day: Morning.

Weather: high humidity. Cool + wet = air falling down slope. What is not also obvious, is that there was a prevailing wind at the photographer's back, which moved the smoke away as well as down.


A good book to read on the subject is: Scent and the Scenting Dog by William G Syrotuck

For more information about Scent Theory with regards to searching with a dog: Hatch Graham’s 1979 Article on Convectional Turbulence and the Airscenting Dog



This article was orginally published on the  Hound and Found Blog