May 25, 2006, Halos, Rime, and Conference Call Time Options

[Kevin_McMahon]

High temperature today: -10 degrees Celsius
Low temperature today: -30 degrees Celsius

We woke up to a beautiful blue sky and a brilliant sun reflecting off the snow. As we looked closer at the sun, we saw a faint rainbow that circled all around the sun. A “halo” is the name for this natural phenomenon. I was not able to capture the entire halo with my camera. Below are pictures of the top and bottom parts of the halo so you get you a feel for what we saw.



Top part of halo, Summit, Greenland




Bottom part of halo, Summit, Greenland


A halo is formed when sunlight is bent as it travels through ice crystals in the atmosphere. It is a common sight in the arctic regions. Robert Perry, the famous Arctic explorer from the United States, even wrote about halos on his last voyage to the North Pole:

On the evening of November 11 [1908], there was a brilliant paraselene, two distinct halos and eight false moons being visible in the southern sky. This phenomenon is not unusual in the Arctic, and is caused by the frost crystals in the air. On this particular occasion the inner halo had a false moon at its zenith, another at its nadir, and one each at the right and left. Outside was another halo, with four other moons." - Robert E. Peary, The North Pole: Its Discovery in 1909 Under the Auspices of the Peary Arctic Club, 1910; Dover Publications, 1986, pp. 175-176

After a breakfast of orange juice, a bagel, and a banana, we walked the ½ mile to our satellite camp. Upon arrival, I saw another amazing site. During the night, small ice crystals had formed over the ropes of our tent and over the surface snow.


Rime at the satellite camp, Summit Greenland


“This is ‘rime’” Mike said. The word ‘rime’ is pronounced just like the word “rhyme”. Rime is very delicate crystals of ice that look like spikes, needles, or feathers. Rime is formed during fogs when supercooled or near-freezing water droplets in the air come in contact with surfaces that are below freezing.
Foggy nights have been common for me at Summit. It used to make me sad because I enjoy the bright sunshine. However, I now look forward to the fog because I know that the camp will look like a winter wonderland when I wake up the next morning.



Fog at Summit Camp, 11:30 p.m.

After admiring the rime, we continued our set up of the instruments to measure the air particles until 10:40 a.m. Here is a picture of me making an adjustment to the “low vol” instrument. See later journal entries for what this instrument is measuring.


Kevin adjusting the "low vol" instrument.

At 10:40, we walked back to camp for a conference call with my 1st period class. Mike, Gayle, and I wished we could speak to more classes, but our schedule only allowed us to call at 9:00 a.m., Decatur, Georgia time. It was great hearing the students’ voices. It made me miss being with them. The students sounded very professional as they asked us questions on the phone. I was very proud of them.


Kevin and Gayle talking on the speaker phone from the Green House. There must have been bad lighting in the Green House because Mr. McMahon looks like he has no hair on the top of his head.

The rest of the afternoon went by quickly. I spent the afternoon responding to questions and writing teacher journal entries. We have had a great number of students writing questions. We enjoy hearing from you and will try to respond to all the questions as quickly as possible. Please be patient if it takes a day or two to answer some questions.

It has been a good day. I feel very fortunate to be able to experience these new sights and to share them with you. I hope to see a sun dog before I leave.

Arctic Fact of the Day: As of 2005, there were four operational traffic lights in Greenland.

Fun things to do at home
1. Find out more information on Robert Peary and reply to this journal entry with what you learned about him. He also made an important discovery about Greenland. Can you find it?
2. What is a sun dog? Reply to this journal entry about what you learned about sun dogs.