Winter precipitation over the Snowy Mountains is largely associated with moist westerly weather systems.  As these systems approach the mountain ranges, the air mass is lifted and condenses further to form orographically enhanced clouds composed of tiny water droplets.  Under certain conditions these droplets remain in liquid form, even at temperatures below zero degrees Celsius.  Water in this form is known as super cooled liquid water ("SLW").

To fall out of the clouds as snow, these SLW droplets need to form ice crystals.  This normally occurs through interaction with tiny airborne particles (like dust or other ice crystals), or when cloud temperatures are very cold.  If there are not enough of these particles, or the temperatures are not cold enough, then not all the SLW droplets are converted into ice crystals and the clouds are considered 'naturally inefficient'.

Under normal conditions, these clouds evaporate as they descend on the lee side of the mountains.  This results in the well understood and naturally occurring phenomenon known as a rain shadow.  This is why areas downwind of mountain ranges, such as the Monaro Plains, tend to be much drier than on the upwind side.

To improve the snow making efficiency of these clouds, additional particles can be introduced into the clouds.  The excess SLW droplets freeze onto these particles forming ice crystals which grow and fall to the ground as snow. This process is known as glaciogenic cloud seeding.

To view the "Cloud Seeding - how it works"  video click here