My tree drips.
We proposed a model for maple tree sap collection. Sap rises as vapor in a tree. When the temperature drops below freezing, the excess vapor freezes. Then, as the temperature warms, the frozen sap thaws to a liquid which is then collected. This liquid sap is in a non-equilibrium condition. that is either collected to produce maple syrup or eventually returns to its equilibrium vapor state at temperatures greater than freezing.
At times, the tree sap drips from the upper branches. We have observed this in mornings and propose the following model.
Overnight, the temperature has dropped below freezing. In the morning as the temperature rises, sap in the thin upper branches thaws more quickly than sap in the main trunk. The hydrostatic head of liquid in the thin upper branches finds a weak point and causes the drips from the tree.