Nucleation nozzles can be classified by how the air and water are mixed at the nozzle. The two main types of nucleation nozzles used are Internal and externally mixed.  

Internally mixed nucleation nozzles mix water and air inside a nozzle before exiting the nozzle into the air. The water droplets are sheared inside the nozzle and projected out of a small opening. 

Externally mixed means water and air are mixed outside two or more nozzles. As these nozzles spray air and water externally, the streams are mixed, and the water droplets are shed outside of these nozzles. 

There’s a lot of confusion surrounding DIY home snowmakers regarding internally mixed nucleators. Many DIY designs use a series of pipes to create an “internally mixed snow gun,” not an internally mixed “nucleator” or nucleation nozzle. Internally mixed snow guns combine water and air inside of snow gun piping instead of inside of a separate nucleation nozzle. Combining water and air inside the snow gun piping is not recommended as regulation is complex, and water and air backflow are common. If water or air is “backflowed,” you can easily damage the compressor or pump. 

Most commercial snow guns use an internally mixed nucleation nozzle since it has superior mixing capacity. When water and air are evenly mixed in the nucleation nozzle, even shearing of water droplets creates millions of properly sized ice crystals.  

Most residential snow guns use externally mixed nucleation nozzles for simplicity and lower cost. These snow guns intersect water and air streams to shear droplets into the correct size for snow formation. The downsize to external mixed nucleators is the smaller distribution of ice crystals produced. Externally mixed nucleators are typically less efficient, and a percentage of the ice crystals produced are outside the proper nucleation range.