Dogs are able to parse out smells because their noses actually have an increased amount of sensors in the nose itself, and those doggy sniffs actually curl through a bunch of “scrolls” inside the nose allowing dogs to separate out details that the air has to share.
This is why dogs are trained to do search and rescue, find illegal drugs, and chase down criminals: because their nose, knows.
National Geographic recently explored this further by doing an experiment where a gentleman attempts to outrun a dog’s nose. Amazing! Video after the jump.