My First Exposure to Rime Ice

2014-10-06 18:06:00.000 – Caleb Meute, Summit Intern

Well I must say, my first exposure to rime ice and deicing our tower has me pretty excited for the upcoming winter. Rime ice is one of the most common weather phenomena up here on the summit, and also one of the big reasons our observatory needs to be staffed 24/7. The phenomenon occurs when super cooled water droplets move over the summit. These tiny droplets of water are able to stay in liquid state at temperatures below freezing, but as soon as they collide with objects that are also below freezing, they instantly freeze to the object. Air particles are trapped in between these particles of ice so they accrue as long and beautiful feathery strands into the direction that the wind is coming from. When the weather is at its worst up here on the summit, rime ice can accrue up to 9 inches per hour! Because of this, a weather observer must suit up and climb a series of ladders to the top of the tower and knock the ice off with a crowbar. This has to be done sometimes up to 3 times per hour.

That is what I was able to do yesterday when temperatures fell below freezing and the cloud layer dropped right onto us allowing a buildup of rime ice to occur. I went to the top of the tower, and with a series of strikes sending vibrations up to the instruments, the ice fell off and onto the deck below. At this point, the instruments were as good as new and measuring the wind speed to their full capabilities. This lasted for an hour, and then the trek upward had to be made again.

Caleb Meute, Summit Intern