Convocation Hall, Ice formation on columns.

Background:
For five days prior to the day this photo was taken, the outdoor air temperature was sustained below -18 degrees Celsius. It is 'now' 11:00 a.m., it is pouring rain, and the air temperature is +5 degrees Celsius. Notice how ice forms all the way around these columns. Why is ice forming on the columns and why does the ice form all the way around the column?

Explanation
Ice forms on the columns because they are still at a temperature below freezing. These massive sandstone columns have a rather large heat capacity (thermal mass) and therefore they do not change temperature quickly.

Ice is forming all around the columns, not because of freezing rain, but because of freezing condensation. Moisture in the air is condensing and then freezing on the cold columns, similar to the way frost appears on a cold popsicle once it is removed from the freezer on a hot humid summer's day.

Generally, thermal mass can be incorporated into building design to dampen the effect of diurnal temperature fluctuations on the indoor air temperature.