Only under certain conditions It is true. In the absence of the conditions, it is false.
1) they must contain some moisture (humid) even though they're not saturated
2) they must be at an altitude at which the air temperature reaches dew point.
Dew point is a measure of humidity like relative humidity is, but the measurement is in terms of degrees of temperature rather than percentage. Dew point temperature is the temperature at which the humidity of the parcels of air begin to condense.
When your two parcels of air achieve dew point temperature, you can still form a cloud.
We formed a cloud in class the other day. We took a jar filled 1/5 of it with hot water, put a match inside and quickly closed the lid and put ice on the lid. Made a cool cloud. Dunno about what your asking but this seemed maybe semi helpful.