How Scent and Airflow Works

How do those dogs find missing people?

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.

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.


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.  These are what dogs smell.

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

Dog Handlers pay attention to air currents.

Skin rafts are carried along currents of air like millions of fluffy dandelion seeds.

We pay attention to physics.   Warm Air rises

and Cool air sinks .  Cold and moisture make air heavier. Your skin rafts first leave your body at about 2mph up in the air traveling along the current of air your 98.6 degree F produces.

Without any air movement

scent diffuses evenly

Diffusion


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

When things are perfect, scent moves predictably like this:

Laminar Flow

Objects and other factors often cause air to move like this:

Turbulent Air Flow

Turbulent air flow causes handlers and their canines to mutter choice words under their breaths.

Different Types of Airflow

Normal Daytime Air

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

Normal Nighttime Air

When the ground begins to cool, air cools and begins to fall. It flows downhill like water.

Coning Plumes