This usually happens after a hot or warm shower because the water vapour in the air becomes a liquid again. It condenses on your mirror. Condensation is taking place!
Small droplets form after taking a shower because of all the steam from the water of your shower.
Where water condenis and froms water fapor eg after a shower there might be water droplets on the mirror
The warm, moist air coming from the shower will condense to water droplets on contact with a cool mirror or bathroom window.
The hot heat from the hot water turns evaporates. Once it reaches or touches a cool surface (mirror), the heat would condense and turn into water droplets. Therefore, water droplets are found in the mirror when you bath.
The steam condenses to form water droplets on the cooler surface.
diffusion
Because the mirror is colder water vapors are condensed on the mirror.
When you take a shower the water droplets have a greater surface area then simply having the water sit in the tub as it does in a bath. The leads to increased evaporation. With more moisture in the air it is easier for condensation to occur on a cool surface such as a mirror.
When the rain and snow are right the small droplets of water in clouds forms larger droplets and precipitation occurs.
When heat and moisture are introduced into a room (like when a hot shower runs in the bathroom), temperature and humidity (the air's water vapor content) increase. The mirror is colder and therefore so is the air right next to the mirror. With the temperature and humidity higher elsewhere in the room - and knowing there can be more water vapor in the air when the air is warmer - the cooling effect of the mirror causes the air right next to it to saturate (since more water vapor can be in the air when the air is warmer). The temperature in this small area drops to or below the dew point, and water begins to condense.
Clouds
Rain
When you get out of shower, there are water droplets on your body. Some of the body's heat is loss to them before they evaporate. So we felt colder. YP