Are clouds forming above a certain height? Are clouds forming above a certain height (300m+) and if they do, how are they staying above that certain height and aren't forming let's say at 20-30m from ground. What keeps them so high? 
 A: You must know that atmospheric temperature decreases with height. As a moist air parcel rises it is thus continuously cooled and beyond a certain height water begins condensing and droplets are formed. A large ensemble of such droplets are what we call clouds.
If conditions are right then clouds form close to the ground too. These are called stratus clouds.
A: @Zero is correct in their explanation, and I just wanted to add a few points.  
Temperature, pressure, and relative humidity all play a part in the formation of clouds.  Both temp and pressure decrease with height.  As air ascends it expands due to the lessening pressure at higher altitudes.  When a fluid expands in volume, its temperature also decrease.  (See ideal gas law PV = nRT)  And as Zero said, the water vapor then condenses to form clouds.  
Also, there must be sufficient water in the air to form clouds.  On hot, dry days, you may see very few, if any clouds.  The relative dew point (the specific temp and pressure, for a given amount of humidity, needed for water to condense and form clouds) will also affect the height at which clouds form.  
Hope this helps!
