Your breath is a source of moisture, and when the temperature is cold, that moisture readily condenses into little clouds. Warm moist air will rise, cooling as it goes. Now all it takes to have clouds to form, is something for the water vapor to cling to. This is airborne particles of dust, smoke, pollen, salt or volcanic ash. These particles are actually microscopic in size.
Clouds are never still, they are always in motion.
Generally, they are moved by the wind, and by rising warm air from the ground heated by the sun. Clouds are classified into ten basic types, and each type generally forms and stays in either the lower, middle or upper atmosphere. They are low altitude clouds, less than 10,000 feet high. These clouds often dissipate at night because they are most susceptible to sinking when the air currents cool. The other lower altitude clouds are stratus, and stratocumulus.