Sure , the air is dry in winter , granted that it doesn't rain (no chance of that here ) ,but that is outside, most people spend most of their time in an inside environment.

Moisture inside could come from people , cooking , hanging your coat up to dry on the rack , inadequate ventilation.

When there is moisture in the air, it has a medium to float around in.

You said yourself that it binds itself to water droplets , it can ride around on the current .