In the small version of this Snack, the air rushing between the spool and the card exerts less pressure on the card than the still air underneath the card. The still air pushes the card toward the spool and holds the card up against gravity. In the larger version, the same principle is at work, holding the plate up against the hole in the box. In an atomizer, or perfume sprayer, you squeeze a rubber bulb to squirt air through a tube. Because of the Bernoulli principle, the air rushing through the tube has a lower pressure than the surrounding atmosphere.
Atmospheric pressure forces the perfume up an intersecting tube into the low-pressure airstream.
The perfume is pushed out of the tube and sprays into the air as a fine mist. The air rushing through the space between two moving trains also has a lower pressure, due to the Bernoulli principle. Sometimes, the higher pressure, stationary air inside each train forces some of the trains' windows out of their frames.