Nacreous Clouds

The crazy cloud invasion (photo by B-nelson).
Over the past couple weeks, we have seen some spectacular cloud formations. They are some of the best I've seen in my life. They are mostly caused by the rising sun illuminating the nacreous clouds against a contrasting sky. Unfortunately, getting a picture is just about impossible. The brightest parts of the clouds require a short exposure, the regular clouds a longer one, and the ground the longest one. The human eye is the best camera ever and none of these pictures truly do the experience justice.


Probably my best picture because it has the blue sky, bright clouds, and a little foreground.
We don't get these clouds in the middle of the day. They mostly appear at 'sunset'. They are supposed to appear at sunrise too, but I haven't seen any yet. I'll keep my eyes open. The rest of this blog is quoted and paraphrased from an explanation by Bec in the WWTP about nacreous clouds. She's knows a lot more about this stuff than I could ever know.


Clouds over McMurdo Sound (there should be blue sky at the top).
The nacreous color of the cloud is a result of diffraction of light through ice crystals in the clouds. In themselves, nacreous clouds are not too uncommon, and can be seen in mid-high latitudes when the atmosphere is cold enough to freeze the droplets of water in the clouds. The nacreous clouds that we see at this time of year in Antarctica though, are a special variety of nacreous cloud – a type 2 polar stratospheric cloud (PSC).


Nacreous clouds over McMurdo Sound.
PSCs are unique to the polar regions. As their name implies, they form in the stratosphere, between 10 and 25 km (6.2 - 15.5 miles). They also only form when stratospheric temperatures get below about -110F. There are several types of PSCs, containing some combination of nitric acid, sulfuric acid and water. The clouds we observed on Monday were type 2 PSCs, which are pure ice – these form in the coldest conditions (-120 F), and are thus the most uncommon. Because they are so high up (Mondays were approximately 20-22 km (13 miles), as determined by the Crary LIDAR), the sunlight is able to hit them before it hits us here on the ground, giving us spectacular light shows. The wavy look of them is due to wave action in the stratosphere, which is often associated with type 2 PSC formation.


Nacreous Clouds over Arrival Heights.
You may have heard that these beautiful clouds are the cause of the ozone hole. This is only partly true – there were PSCs long before there was an ozone hole (sightings are recorded in the diaries of the first winter-over group). However they are a key ingredient because chlorine gases are able to react in the clouds and produce ClO which eventually goes onto react with the ozone. It can destroy thousands of ozone atoms. In November/December, the warmer, ozone rich air will flood into the region and the hole will disappear.


More crazy clouds that are missing the bluer skies.

Hot Tub Tuesday!

Nacreous clouds over McMurdo Base from right outside my office.
Tuesday was the first day that I've seen a lot of nacreous clouds over town. I thought they were always colorful, but apparently they only get their colors if sunlight can reach them. You can see a little bit of color if you click on the picture to zoom in on the upper right clouds. When the sun is closer to or above the horizon, the light should be able to reach the clouds and light them up.


Steam room?
Unfortunately, I didn't get out for a hike on Tuesday to take any pictures, but I did get to spend some time in a hot tub. We've had one all winter, but I just never made it a priority to go. I think it had to do with getting wet and then needing to go back outside to get to my dorm. I was finally talked into it on Tuesday.


Mosquito net or ambiance (yes, there was cheap editing done to this photo)?
The hot tub was much better than I expected. I thought it would just be a small, dark room with a hot tub. It was much more. It had a small hot tub, of course, stereo, table, towel rack, couch, and even a little room to stretch out if you liked your neighbors. It was hotter than hot and I was in there for so long that my toes got raisined for the first time in almost a year. Definitely a good time and the damp scurry back to my room wasn't that bad either.


Happy hot tubber.

Sunday Night Surprise

The brightest aurora I have ever seen.
On Sunday night as I was heading home to bed, I saw the brightest auroras that I have ever seen in my life. I was walking across DJ to my dorm and could see a white cloud moving above me. Normally, a half moon is enough to obscure any auroras. If the full moon doesn't do it, then the street lights in town certainly will so I was astounded when that cloud started moving up and down like an aurora.


Auroras over the Hut Ridge Trail.
I rubbed my eyes to make sure they weren't playing tricks. When they weren't, I ran the rest of the way home, put on my ECW, and then grabbed a bicycle to head down to Hut Point. I could see the auroras from town so I figured they would be even better from a darker spot. They faded quickly, but didn't disappoint one bit. The aurora over the ice runway was so bright it lit up the ice a little bit. I thought I imagined it, but I was told by someone who has seen brighter auroras in Anchorage that they can do that. Apparently, Anchorage is right in an auroral oval so they regularly get fantastic displays that dwarf what we get here.


Menacing fog . . .
I was out less than an hour before the auroras faded and a fog moved into town. I'm not sure why, but we've had a bunch of fog this week. It might be the colder temperatures. Today, we are down to -32F/-76F wind chill. It is a good day to be an indoor PC Tech. The fleet ops are working hard.

This post is for Nancy who can't seem to get enough aurora pictures.

Recently Expired Everything

A box outside our retail store.
As most of you know, the expiration dates on many goods are flexible. You can usually eek a few more days out of milk and even more out of other goods. It all depends how far you are willing to go. Down here, the frozen dry climate lets us go much farther. Consequently, most of the food we eat is expired.

The bulk of our supplies are shipped to us once a year in February via container vessel. The supplies that fill those containers arrive in Port Hueneme, CA year round. If an order gets there in March, we won't see it on ice until the following February. Then, the winter crew will unpack it for use. However, it could be used anytime up to and including the next February after that - almost a full TWO YEARS after the item was purchased. People often talk about ‘The Winter of Flank Steak’ or some other time period where they were trying to get rid of stockpiled food that was even older than two years.

I've heard all types of stories that go along with our expired goods. One day, the store was stocking tortilla chips and decided what they were stocking couldn't go on the shelves. Why? It wasn't expired yet and they had a lot of other expired things that they had to get on the shelves and out the door. The box at the top of this blog is from the store. I can't even guess how old Ramen noodles have to be before they are put in that box. Just last night, they were giving out free packages of Lay's Stax. When I asked someone how old they were, they said they weren't too bad, only September 2007. Eleven months past expiration isn’t too bad? Back home, I think that would raise a few eyebrows. Down here, it’s normal.

Over the summer, I heard that since we were serving up expired and cheap quality fish, a cook was tasked with seeing if they cook it and make it edible. I heard it passed. The flip side to all of these expired goods is that unless someone told me what we had was expired, I wouldn’t have known. That might be because I eat so many preservative filled meals at home or that I'm just clueless. Maybe a little of both.


A view that will also soon expire. Am I going to miss the dark skies?