what is the difference between snow drift and snow sliding
 

what is the difference between snow drift and snow sliding?
i thought they were always the same, but the canadian code distinguishes between both and requires a 50% increase in snow drift values to account for snow sliding. can anyone clarify please?

a snow drift is basically when you have an obstruction such as a higher roof that is flat. if this roof has a slope to it, and snow can slide off of this roof onto the lower roof, that is sliding snow.
gotcha. thanks.
drifting occurs at obstructions such as a large air handling unit or screen wall, at parapet walls and at the wall between a high roof and a low roof.
drifts can be formed from windward or leeward winds. the upper and lower roof surfaces can be sloped or level.