Glaze

2009-12-28 05:34:18.000 – Mike Carmon,  Staff Meteorologist

Generally, the word “glaze” has a positive connotation to it.

Glazed donuts are some of the best!Glaze icings are always popular on sweet treats.Glazing agents are added to foods to give them a shiny appearance or to protect them.

However, yesterday brought with it a form of glaze that was not so pleasant-glaze ice.

We often talk about rime ice, and how it forms-when the summit is in the fog, and temperatures are below freezing. All of the liquid water droplets that make up a cloud will freeze to any surface they may come in contact with. However, when temperatures are very near freezing, that light and feathery rime is replaced with a thick and heavy glaze ice. Saturday night’s temperatures and moisture content were perfect for a significant glaze icing event on the summit.

Temperatures rose through the 20s throughout Saturday night and the wee hours of Sunday, and a southeast flow fed plentiful moisture into the region. As a result, glaze ice began to form around 10 p.m. At first, the accumulation was nothing out of the ordinary-about 1-2″ per hour. Then, when I went to the tower for the midnight observation, I could not believe my eyes! There was nearly 7″ of glaze ice coating the posts that I had de-iced approximately one hour before! It was by far the fastest accrual of glaze ice I had seen in my lifetime. The pitot-static anemometer and wind vane were encased in this thick coating. It took many, many whacks of the crowbar to get rid of all of this ice.

This trend continued for the remainder of the night and into the day yesterday. After taking a rubber-mallet to the A-Frame to knock the large chunks of glaze off of it yesterday morning, I happily turned de-icing duties over to Stacey and Scott. Unfortunately, when freezing rain and ice pellets moved in during the late morning hours, the glaze that formed on our microwave dish knocked out the internet connection. As I slept and recharged my de-icing muscles, Stacey and Scott worked diligently to restore the connection, which they ultimately did after multiple attempts.

The glazing finally ceased yesterday evening, but the damage had already been done. Everything on the summit is coated in layers of glaze ice, feet thick in some places (the greatest accumulations are in places that were most exposed to the winds)! Needless to say, I’m sure all three of us have seen enough glaze ice to last a lifetime, and look forward to the colder temperatures that yield the feathery and much lighter rime ice! I can only hope the next time I speak of glaze, a sugary treat will be involved somehow.

Mike Carmon,  Staff Meteorologist